Learn how to properly process acorns for eating and try out a delicious vegetarian meatball sub where they star as the secret ingredient!

New to foraging? Learn more about ethical and safe foraging (plus how to get started) here!

It's *October Eve*! (Is it any surprise that I get really excited about Spooky Season? ;) ) Ahead are lots of autumnal delights, from acorn sandwiches to candy bones to the cutest tiramisu you ever did see... but this is, most definitely, the post to begin with. Here's the deal: I LOVE ACORNS. They are free and plentiful, plus they have a rich maple flavor that is so cozy and warm and positively ambrosial! The smell of a pot of acorns boiling away on the stove has to be one of the best smells of fall, for me. And since I love acorns so much, they'll be featured in lots of recipes to come! Which means, it's about time you learned how to process them. You're going to want a stash of acorn flour in your freezer for future recipes, trust me. ;) So come with me as I guide you through all sorts of different ways to process acorns to be both delicious and edible, and at the end of all that work you can treat yourself to a flavorful, hearty sub sandwich smothered in tomato sauce and cheese (regular or vegan) - the ultimate comfort food. Are you ready??



Have you ever felt the urge to gather up a bunch of fallen acorns in the fall and shove them away into jars like a busy little squirrel? No? Just me?

Well, acorns actually ARE edible and delicious, but need to be processed in a way that leaches the bitter tannins from them before they are safe to eat (not that you’d want to eat them raw, blech!) The good news is that with a little patience and hard work, you can leach the acorns of those tannins and create something delicious. I’ll walk you through some of those processes so you can decide which one will work best for you. Remember that many foods require some processing - but with foods you forage yourself, you’ll be doing the work instead of buying pre-milled and prepared flours from the store. Get some friends to help you and make a party out of it! 

First of all, acorns from different species of oak (and even different trees) can vary drastically in tannin levels. My recommendation is to gather a few acorns from several different oak trees, then take the *teensiest* nibble from each. Whichever one is least bitter and drying will be the tree to go back to, since less tannins means less work. One thing I have noticed through the years is that there is a pretty strong flavor difference between red oak varieties and white oak varieties:

Red oaks: these trees have leaves that have pointed lobes. The inside of the acorn caps can appear to be lots of tiny hairs. In my experience, acorns from red oaks have a more pronounced warm, maple-like flavor, but they also have more tannins.

White oaks, on the other hand, have leaves with rounded lobes. The inside of the acorn caps are smooth. Generally, white oaks have a more mild flavor but also less tannins. That’s because their maturation rates are different! White oak acorns mature in one season and begin germination in the fall, while acorns from red oaks generally take two seasons to mature and begin germination the next spring.

Another interesting thing about oak trees is that they have cycles larger than yearly productions of leaves and acorns. Oaks have “mast years,” which are years that they produce an abundance of acorns. (That’s why your favorite tree might have very few acorns one year and buckets the next.) This is an evolutionary trait to help oak trees reproduce. Since their acorns are so desirable by little critters, they hold off on producing them until the population of these animals goes down, so that when they produce acorns again, they produce more than could be eaten by those animals, ensuring that plenty are left behind to sprout into a new tree. (That’s one theory, anyways. Botanists still aren’t exactly sure what causes mast years, and whether or not the trees coordinate their seed production.) Just note that you won’t get a consistent crop every year from the same tree; you’ll likely need to explore a bit each fall to find that year’s tree to gather from!

Once you determine which tree you want to gather from (and whether you’re up for the challenge of a red oak), look for this season’s acorns on the ground. The nuts should feel smooth and heavy, with no evidence of mold or rot. Rinse them if they’re dusty or dirty and discard any acorns that float, then start shelling them. It’s best to do this soon after gathering acorns, when they are still moist and fresh. I just use a small hammer and a hard surface and give each acorn a good whack, then pull the nutmeat out. Keep a big bowl of water handy and put the acorn nutmeat directly into it to keep it from browning. I’d also recommend wearing gloves for this process, since the tannins in the acorns can be very drying to the skin.

Once you have a bunch of shelled acorns, it’s time to decide what method you want to use to leach them. There are two basic categories:

Cold Leaching: this uses cool water to wash away the tannins. The pro to this method is that it leaves more of the starches behind, so the resulting acorns will make better flour for baking with, thickener for puddings or soups, and will generally have a bit more flavor. The con to these methods is that they typically take longer than hot leaching.

Hot Leaching: this uses multiple changes of boiling water to leach the tannins from the acorns more quickly. You do lose more of the starches during this process, so the resulting acorns are better for pickling, adding to soups or stews for texture and protein, or using in recipes like the one below for meat substitutes.

Here are several methods to try out:

Cold Leaching:

The Stream Method:

If you live out in the woods and have a clean stream running through your property, you’re in luck! This may be the original method of leaching acorns, developed by the Native Americans that used them as a big part of their fall and winter diet. Simply put your whole or roughly chopped acorns into a mesh bag and submerge it in the stream. Pick an area where the water is deep enough that the bag doesn’t touch the streambed and the water can easily pass over the whole bag. Take out an acorn, rinse it in clean water, and take a little nibble about once a week. When the acorn no longer tastes at all bitter, your acorns are ready to use. Just wash in clean water first. The acorns can then be eaten fresh, dried, or ground into flour.

The Toilet Method:

This is similar to the stream method, but instead takes advantage of the water circulating through the back of your toilet. It sounds gross, but remember that the water in the tank is just normal tap water! I recommend emptying the tank, scrubbing it out really well, then placing your acorns in a mesh bag hanging down into the water. They’ll leach tannins with every flush. To test, do the same as the stream method, making sure to rinse with clean water before taking a nibble. The acorns can be ready in as little as 24 hours or up to several days. One major pro to this method is that you won’t be wasting any water; it’s making use of water that will be used regardless.

The Fridge Method:

Chop your acorns very fine (or use a meat grinder to grind into small chunks.) Fill a large jar ¼ full of acorn chunks and then top with clean water. Put on the lid and shake it up well. Let the acorn meal settle. Twice a day, carefully pour off most of the water, stopping when the top starchy layer of acorn starch starts to pour out. Then refill, shake, and repeat. This process can take quite some time and it does use a fair amount of water to leach your acorns completely.

The Shower Method:

This is my favorite way of processing acorns for flour, and is based on a method taught by John Kallas of Wild Food Adventures. It’s by far the fastest way I have found to turn raw acorns into ready-to-bake-with flour, though it does take a lot more hands-on attention and some special equipment. Here are the steps:

1. First, use a meat grinder to process your acorns into a fine meal. Spread it out on a clean non-stick surface and let it dry completely. (You can use a dehydrator to speed up the process, just make sure you keep it on low heat so you don’t cook the starches.)

2. Once the meal is totally dry, use a flour mill to grind it into fine flour. The finer, the better - tannins will leach out of pieces with a large surface area much more quickly. For small batches you can use a food processor or spice grinder, just be aware that acorns are pretty tough on the blades of these devices. Sometimes you can even rent flour mills for a day or two if you have a big batch to process.

3. To set up your leaching station, you’re going to want to find some containers that can drain out the bottom. Buckets with spigots in the bottom that are used for brewing beer are a good bet, but you could also just cut the bottom off of a cheaper bucket as well. I usually use 3-5 buckets at once, depending on how much flour I have to leach and how big my shower is. To prep each one, take a single layer of clean cotton muslin and place it over the opening of the bucket. Secure with a couple of large rubber bands so that it is tight but has a slight amount of give. (You’ll want some room for the fabric to fill with water without overflowing.) It’s important to use the right fabric for this; if the fabric is too tightly-woven it will take ages to drain, but if it’s too loose you will lose a lot of your flour. Position the buckets in your shower.

4. Sift about ¼” of acorn flour across the surface of each piece of stretched muslin. Spray with a spray bottle to moisten both the flour and the fabric, then turn the shower on cool. Let it run until the water is coming up to the lip of the bucket; you don’t want any of your acorn slurry to overflow. Turn off the shower and let the water drain through, taking the tannins with it. Continually check the buckets throughout the day, turning the shower on just long enough to fill the fabric and then off again. You may need to rotate the buckets so they all get an even fill of water. Every couple of times, sample the acorn paste; when it no longer tastes bitter, it’s done leaching. Then you can carefully move the buckets out into the sun and let the flour air-dry, then re-grind it to a flour.

Hot Leaching:

Two Pots:

This method is relatively quick and easy, but it will take your attention for a while. If you want to pickle, roast, or enjoy your acorns whole, the process will take longer. I recommend chopping them up into even ¼” pieces if you’ll be using them ground, infused, or mixed into things like the acornballs below. Remember, the more surface area, the faster the tannins will leach. Bring two large pots of water to a boil. Add the acorn pieces to one pot and boil until the water is dark. Strain out the acorns and immediately plunge them into the second pot of boiling water. Fill up the first pot with more water and bring to a boil while the acorns boil in the second pot. Continue this process, being careful to keep the acorns hot at all times, until the water is nearly clear and the acorn chunks no longer taste bitter. (Letting them cool can lock in the tannins you’re trying to remove.)  The time this takes varies on your acorns; sometimes it’s half an hour, other times it can be the whole afternoon. Now you can strain the acorns and let them cool before cooking with, freezing, pickling, drying, or otherwise preparing them.

General Tips:

1. Consistency in size is important for any leaching method. Whether you are leaching whole nuts or fine flour, try to get the particle sizes as consistent as you can. That will make it easier to assess when the tannins have all been leached and save you time and energy trying to leach bigger pieces when the smaller ones are ready.

2. Acorn flour will last longer if stored in the freezer. Make sure it is fully dried, then pack it in airtight containers or vacuum seal it into bags.

3. The tannin-rich water leftover from acorn processing makes a great mordant for fabric! If you have clean pieces of fabric you want to dye with natural dyes, soak them in the acorn water for a while, then dry them out. They’ll be ready to absorb dye better when you do dye them.

4. It’s best to cook your acorns in some way prior to consuming them, especially if you used the stream or toilet bowl leaching methods. Anything baked with the flour is fine, but if you want to eat acorns as a nut, roast them at 350F until lightly browned.

Acornball Sandwiches:

After all that work, you must be hungry! This recipe is a great way to enjoy the bounty of acorns in a plant-based comfort food delight. Their nutty flavor and chestnut-like texture work really well in vegan “acornballs” smothered in marinara sauce and eaten with some soft buns and optional plant-based cheese. The acornballs are a little softer and less chewy than traditional meatballs, but they have a great texture and nutty flavor with umami undertones that makes them absolutely delightful. This idea was inspired by this fantastic post by HungerandThirstforLife, with loads of ideas for “meatballs around the world.”

Ingredients:

1 cup hot-leached acorns, chopped

½ c. cooked white beans

4 Tbs. dehydrated potato flakes

½ tsp. Baking powder

½ tsp salt

2 cloves garlic, minced

2 tsp. Dried bee balm (or oregano)

1 tsp. Wild fennel seeds

2 Tbs. olive oil

2 Tbs. flax meal, mixed with 2 Tbs. hot water (let sit for 5 min.)

Boiling water, as needed.

Directions:

1. First, prepare the eggless binder: mix the flax meal with the hot water and let sit while you prepare the rest of the mixture.

2. Roughly mash the beans, then mix them with the acorn pieces.

3. Whisk together the potato flakes, baking powder, salt, garlic, bee balm, and fennel seeds. Add the acorn and beans, olive oil, and flax. Mix together well and add a little boiling water as needed to make a mixture that can be formed into balls.

4. Roll the mixture into 1” balls, then pan-fry them in a skillet with a little oil until they are browned on all sides.

Sandwich Assembly:

Buns (gluten-free if desired)

Garlic

Marinara sauce

Cheese or vegan cheese

Chopped fresh parsley, for garnish

Directions:

1. Toast the inside of the buns under the broiler, then rub with raw garlic.

2. Add meatballs to fill each sandwich and add marinara sauce

3. Top with cheese of choice

4. Broil until the sandwiches are warmed through and the cheese has melted.

Substitutions: To make the Acornballs vegan, substitute “flax eggs” for the eggs in the mixture (mix 2 Tbs. flaxseed meal with 5 Tbs. water and let sit while you prepare the other ingredients.) Substitute Oregano for Bee Balm and Fennel seeds for WIld Fennel. Chopped walnuts or pecans can be used in place of the acorns in the recipe.

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