Some species produce huge acorns with low levels of tannic acid, while others grow tiny acorns that are loaded with it. While tannic acid has some outstanding medicinal benefits for topical problems, it’s an irritant to the GI tract. You just have to get rid of the tannic acid, which may be abundant or light – depending on species and growing conditions. Luckily, tannic acid is water-soluble, and we can remove it with a soaking technique that most people call “leaching.” Tim MacWelchYou could follow any cookie recipe, swapping out the wheat flour for acorn flour, but this one is our family favorite.