Andrew:

Yes, it's a five step process. Gather, husk, winnow, grind, leach, cook.
Acorns contain tannin (tannic acid), which imparts a bitter taste. This is
leached out with water. There are maybe a dozen different oak varieties in
California (compared with two in Europe). Acorns of the black oak were
favored in So. Cal.

I've yet to taste any acorn meal as I haven't found a source yet. I may have
to go to the mountains this fall and gather them myself!  The grinding
process is interesting, as basically the natives ground everything to a meal.
Anything, like nuts, seeds, ants, insects, can be ground up in a pestle and
mortar (called mano and metate (or mortero) here). The metate is a grinding
stone with a depression in it, which is deepened with use. The mano is a
small stone held in the hand.

They would even grind up small rodents and birds in this device, bones and
all. This is how they got their calcium!

Basically you end up with a thick soup like porridge, which is cooked in an
earthenware pot on the fire. This soup was eaten with small wooden or bone
spoons. Or it could be sun dried, or baked, to form cakes, which can be
carried. The desert Indians would do this with the beans of the mesquite
bush. This stuff is highly nutritious -- it's packed with proteins and fat,
and some carbo.

I've tried to simulate the process using a blender. I've used sunflower and
watermelon seeds, and hazelnuts, which was the closest I could get to acorns.
This worked quite well. The blender does not grind as fine as one could get
with a metate, I think. Add water, and set on liquefy, until turned into
porridge. Simmer for 20-30 mins. Add some salt, if you use unsalted seeds and
nuts. I dried the resulting stew in the microwave to make the cake. People
were surprised at how tasty this turned out. And very filling -- you can't
eat much of it, probably because of the high fat content.

Charles