Another year of cooking, experiments and insights, and I still don’t think I’ve come even close to unlocking the potential of acorns. Yes, acorns. You know, those things that fall from oak trees?

Readers of this space know I’ve written extensively on collecting and eating acorns, how acorns are eaten in other world cultures, and on the important role acorns play in a wild diet. I also have a series of acorn recipes elsewhere on this site. What else was there to write?

Lots, apparently. For starters, there are nearly as many ways to get the bitter tannins out of the acorns as there are people who eat them, which is to say, um, at least a dozen. Different species of acorns also taste different, and will act differently in the kitchen. Some are oily, some more floury, some light, some dark.

At their core, however, the best reference point I can give you for all acorns is the chestnut. Both nuts are slightly mealy, share the same color, have a similar nutrient content and act pretty much the same in the kitchen; chestnuts taste a little sweeter, but acorns caramelize easier.

A few weeks ago I went to my acorn spot, a grove of giant Valley oaks that regularly drops tons of acorns — not an exaggeration. This year, however, the trees did not set. No acorns to speak of. None. Oaks will do this, however, so a forager needs to have several spots scoped out in case one doesn’t pan out.

Fortunately this year I had help. A friend of my friend Jim’s has a horse paddock underneath lots of oaks. Oaks that were dropping acorns something fierce. Every morning she picked up the acorns, because apparently horses get sick if they eat too many. Did I want them? Hell, yeah I did! So I met Jim and he handed over nearly 30 pounds of acorns.

Sadly, almost a third had the tell-tale hole in them that means an acorn weevil ate the nut. These acorns went outside, food for squirrels. Another portion were from an oak that set tiny acorns, not really worth bothering with. But the bulk of the remainder were acorns from California’s blue oak, a “sweet” oak species whose acorns require minimal processing.

Last season I ran out of acorn flour, so I was determined to make more this time. And this time I decided to use cold water to leach out the bitterness in the acorns; last season I used boiling water. Boiling water happens to leach out some important starches in the acorns, and the resulting flour won’t stick to itself as well as flour made with cold water.

This matters, because acorn flour lacks gluten — so you need every little bit of stick-to-itive-ness you can get. I also found that cold-leached flour tasted more acorn-y, and was lighter in color.

The catch? It takes many days to make cold-leached acorn flour. Here’s how:

• Crack your acorns into a bucket of water, then extract them from the shells into a large bowl of water. Keeping the nuts under water helps preserve the light color — acorns oxidize and turn dark easily.
• Fill a blender half full with acorns and cover with fresh water. Buzz the hell out of them, until you have what really, really looks like a coffee milkshake. Far be it from me to suggest a truly excellent practical joke right now…
• Pour the mix into large jars (big Korean kimchee jars are great) about halfway and top off with more water. Seal the jar and shake everything up. Put the jar in the fridge.
• Every day, pour off the water, replace with fresh water, shake well and set back in the fridge. You’re done when the acorns taste boring, not bitter. The blue oaks took a week.

Now you need to dry your flour. Start by pouring everything into a colander with cheesecloth set in it. Gather the cheesecloth and squeeze it tight to extract as much water as you can.

Now spread the still-damp flour on a large rimmed cookie sheet. Break up any clumps. Blue oaks have a lot of oil in them, and you will get “acorn butter,” a very light, clay-like substance that you can skim off or incorporate into the flour. I mix it in, as it has a lot of flavor. Acorn butter clumps a lot, so you will need to break it up small.

Put the cookie sheet in an oven set on “warm.” Don’t get the heat higher than that, or you will bake your flour, and you don’t want that. A food dehydrator ought to work, too, but I don’t have one.

Finally, you need to grind the dried flour one more time. Use a heavy duty coffee or spice grinder. Grind the flour into a fine powder, which took me about 35 seconds. Store in the fridge or freezer, as the fats in acorn flour go rancid rapidly.

Sounds like a lot of work, right? It was. A huge amount of work that made me very, very aware about how we take regular wheat flour for granted. I can guarantee you I will not be tossing around acorn flour the way I would with all-purpose. It’s too precious.

And good. I made acorn pasta last year with the hot-leached flour, so I decided to switch to acorn spaetzle this year with the cold-leached flour. I served the little dumplings with venison sauerbraten.

I used the sauerbraten recipe I developed for Elise at Simply Recipes, but I cooked the venison roast sous vide at 140 degrees for six hours. It was meltingly tender and perfectly cooked. I highly recommend this technique.

You can really taste the nuttiness and the warm, “dark” flavor of the acorns in the spaetzle. It was my favorite acorn dish so far.

Until I made acorn soup.

I did not make this with acorn flour. I did it with acorn “grits” I made after hot-leaching the last of my acorn stash. You hot-leach the bitterness from acorns by putting the nuts into a kettle of water and bringing the water to a boil. Pour off the water and repeat until the acorns are no longer bitter. It took me six changes of water to get all the bitterness out.

Why make grits? Well, you can add them to a regular soup like you would a potato — I did this with a grouse soup I made last year — or you can use it as a base for a smooth soup, like the one I did this week. This soup started with carrots, onion, dried porcini and celery cooked in butter, then I tossed in some pear brandy and wild goose stock, added the acorn bits and simmered for an hour. A trip to the blender to puree came next, then a little water, a little salt, a dollop of creme fraiche and you’re done.

Was it good? You bet it was good! The soup has a woodsy, almost caramel taste to it, is smooth as a baby’s behind and smells like winter. If you go to the trouble to make this soup, I guarantee you will not be disappointed.

MORE ON ACORNS

• Acorn Muffins, from Book of Yum
• Acorn Bread, by Amber Dusick
• Petit Chef’s Spiced Pickled Acorns