I can’t say enough about how The Noma Guide to Fermentation is livening up my kitchen experiments, but I was fairly sure that I wouldn’t care much for ordinary lacto-fermentation. All fermented pickles and sauerkraut are made by this method, and with the exception of kimchi I’ve never really taken to any of them. But then I bought a couple of pounds of organic cremini mushrooms because they were on sale cheap and I’m a sucker for a bargain, and had to figure out something to do with them. I tried slicing them, tossing with 4% of their weight in salt, and packing into quart mason jars under pickle weights. I set them aside loosely covered, and when I next paid attention to them a week later the mushrooms had shrunk down by half and the jars were filled with fluid. I sniffed the contents, and was surprised at the strong mushroom aroma. I tasted the fluid and it was salty and had a full mushroom flavor. So I started to experiment.
This soup also contains other recent and past experiments. If there is one thing that I want readers of my blog to do, it is play with their food. Taste, and if the tastes go well together, it doesn’t matter whether you ever saw a recipe quite like it before. The flavor of mushrooms and black garlic seem made for each other, and I wanted to try the combination out. I put about a cup of dried porcini slices in hot water to soak. While they soaked, I started the cooking with two cloves of fresh garlic finely minced and eight peeled cloves of black garlic chopped very coarsely. I melted a couple of tablespoons of butter in a saucepan, and added the two garlic types and three slices of bacon sliced 1/4” wide. I sautéed these ingredients slowly over medium heat until the fresh garlic was cooked but not yet coloring, and added a quart of very good chicken broth, the soaked porcinis and their strained soaking water, half a cup of the fermented creminis and their fluid, and a tablespoon of dry sherry and two teaspoons of Red Boat fish sauce. This mixture was brought to a slow boil, and turned down to a simmer for 20 minutes. Meanwhile I peeled another eight cloves of black garlic and pounded them to a smooth paste with a good pinch of salt. When smooth, I pounded in a tablespoon of fermented mushroom liquid, a tablespoon of boiled-down kombucha, and a tablespoon of red wine vinegar. When the soup was served, a good dollop of this paste was put in each bowl, to be stirred in by the diner. Of course you could just add it to the soup in the pot, but the pleasure of smelling the rich, complex fragrance as the paste melts into the soup would then be lost to all but the cook.
Be aware that lacto-fermentation only preserves food up to a point. After a week fermenting on the counter, the cremini juice is at peak flavor in my opinion. If left at room temp it may go on to develop musty off-flavors. In my kitchen, at the one-week point it goes in the fridge.
I always use quart wide-mouth mason jars for lacto-fermenting. There are wonderful crocks made especially for the purpose, but I don’t want that much of any one product, so I stick with my jars. Good pickle weights will simplify your lacto-fermenting and help prevent mold. Good weights are glass, solid and heavy, smooth on the bottom, and have a handle on top so that you can get hold of them. Cheaper weights are often hollow on the bottom, creating an airspace that invites mold, and aren’t heavy enough to keep the fermenting veggies submerged. Good ones can be bought here or from other sources. I have one hand-thrown stoneware pickle weight that I love, and have also used smooth rounded rocks of the right size after putting them through the dishwasher. This last is unscientific and probably unsanitary but I bet our ancestors did it too.