Acorns are the nut of an oak tree. Acorns were part of the staple diet of the Native Americans. Acorns must be soaked and pounded before eating to remove toxic tannins. Most acorns were ground into meal and made into a type of bread. While we have large quantities of acorn bearing oak trees across the U.S. there is little use of the nuts used for human consumption in the U.S.
The acorn nuts are a good source of protein, fats and carbohydrate. "Acorn flour, is dense and has no gluten, so it needs at least a 1:1 ratio with wheat flour if it’s going to rise. (Civileats.com)". Acorn flour itself is naturally gluten free.
However, acorns are still eaten in some Asian cultures including China and Korea. Specifically in parts of rural Korea the acorn was consumed as a backup source of carbohydrate when rice was scarce. Some of the acorns are hand gathered, mostly by woman but much of the acorns are imported from China and Africa as well as a handful of other countries. Read about the flavor and processing information below.
Before acorns are leached to remove the tannins they taste sweet initially then the flavor turns to bitterness. According to Lincoln Smith (acorn expert) once leached the flour when cooked takes on a sweet, nutty flavor.
This process may vary from culture to culture but here are the basics:
In Korea the most popular use for the acorn is to make a type of tofu named "dotorimuk". Additionally there is come production of acorn pasta and even acorn pancakes. Source: U.S. Forest Service.
Another interesting use for acorns is a type of coffee produced in Lithuania made from the acorns of the white oak trees. The acorns are leached in milk and go through a couple rinses of water. Once leached and boiled again in milk you end up with a brownish brew with a nice nutty flavor. Read more about this from Gastro Obscura.
Here are some good sources for information about gathering and cooking with acorns.
How To Process Acorns Into Flour - Video
Cooking With Acorns - Good article from Earthroots about preparing home gathered acorns including a recipe for Acorn Pancakes.
North American Indian Recipes - an excellent source of information and native American recipes using the acorn from The People's Path.
This recipe for acorn bread uses the 1:1 ratio of acorn flour to all-purpose flour as recommended above.
Preheat oven to 400F
Sift the dry ingredients together into a small bowl. In a separate bowl mix the egg, milk and oil together. Now combine the dry ingredients with the liquid ingredients and stir just until the dry ingredients are moistened (like you would muffins).
Pour the mixture into a greased loaf pan. Bake for 30 minutes or until a toothpick inserted in the center of the loaf comes out clean.