Last year a good friend went through the laborious process of making acorn flour. I was intrigued, being the urban forager that I am, but definitely put off by the amount of work. Then she showed up one day with a slice of bread she'd made and I've been determined to try making it ever since. The flavor was so intense, rich and flavorful so I was surprised that she only used a third of a cup of the flour along with a melange of unbleached white and whole wheat.
It's acorn season and I've been getting an education in oak trees. I've learned to identify white oaks, which apparently are some of the sweetest acorns to find. They're also a substantial size making them worth shucking. I've collected a couple of pounds from three trees up in Prospect Park and am planning to go back for more. I can already tell that this hefty bag of acorns is only going to make a small amount of flour, so as long as I'm putting in the time I might as well go all the way and collect more.
I've gotten a lot of information on how to do this from Hank Shaw of Hunter Angler Gardener Cook
. His biggest piece of advice on collecting them was to look for little worm holes and discard those. Acorns are bitter from their high tannin content and the tannin has to be leached out. I've seen a lot of different versions on how to do this but his cold water leaching method seems to be the most reasonable.
First you have to shuck the acorns - under water! With the pointed end facing up I used a hammer to crack the acorns and then threw them into a pan of water. The hulls are kind of elastic so some come off the nut quite easily while others need to be wrestled with. Then I threw them in a blender filled with a couple of cups of water. When I had about two cups of acorns in there I blended them up to make what looks like a coffee milkshake. The sludge was then transferred into a large jar and filled with more water and put in the refrigerator. Every day I poured off the water and added more, shook it up and placed it back in the 'fridge. I did this for a week and then lined a colander with cheesecloth and poured the whole mess through. Pulling the edges of the cheesecloth together I gently squeezed out as much water as I could.
Now the goal is to dry out the mass. Spread it evenly on a cookie sheet (preferably one with sides) and set the oven on low. Mine doesn't have a low setting so I warmed it to the lowest temperature and then turned it off and set the cookie sheet inside. You don't want to bake the acorns, just dry them out so keep your eye on them. It took a couple of hours of turning the oven on and off and checking periodically before it was ready. I used a coffee grinder free of coffee residue to grind the dried mass into flour. I have a separate one I use for spices so this worked perfectly. In small batches try to grind the flour as fine as possible.
It's a lot of work for a small amount of flour, that's for sure. While the first batch was drying in the oven I started shucking the second batch. I figure I have three more trials to go and I'm hoping to be done in time for holiday baking. I'll let you know how it goes, and whether it's worth the labor. If it's as delicious as I remember I'll be thoroughly gratified. Hank Shaw also has some delicious sounding recipes on his blog which you can find here