I don't know if Mitsuwa has always carried sake lees, or sakekasu, but they do now, and perhaps it's more than just coincidence that winter is the height of sake brewing season, and therefore just the right time for this by-product of the process to show up. Why should you care? Well, these are solids left over after the sake is separated from the fermented rice. Fermented rice? You mean koji? That's right. The same stuff chefs are using to amp the umami of everything from burgers to spaghetti carbonara to baked goods.

But pressed, pasty sake lees have something extra—the unmistakably sweet, funky taste and aroma of the sake itself. And cooks are currently using it to make soups, pickles, marinades for fish or meat, or in the case of WD-50's Wylie Dufresne, sakekasu tahini with grapefruit shallot jam. Mike Sheerin of Trenchermen told me they've used it for everything from pasta to mayo to soubise to bread. One of the simplest things you make is amazake, a sweet, warming, ginger-spiked winter beverage that's sort of like a combination of horchata and champurrado and Korean makkeoli. Simple recipe for it here.

The next simplest: marinate fish or meat. At Mitsuwa, a 10.5-ounce package of Hakutsuru sake lees—from "Japan's #1 selling" sake brewer—is $3.49, just enough to make a batch of amazake and marinate a hamachi loin. Just take about six ounces of sake lees and bring it to room temperature. Chop it up and mix with about 1/4 cup sake or shochu, 1/4 cup mirin, and two tablespoons of white miso. Smear the fish (or chicken or pork) with the marinade and refrigerate for one to two days. When ready to cook, wipe off the excess marinade or it will burn. Broil the fish until just cooked. Give it a squirt of some citrus and enjoy. You''ll be able to taste the familiar, sweet burn of sake embedded in the flesh.

Mike Sula writes about cooking every Monday.