If the wonderful complexity that is Chinese cooking could be reduced to one essential flavour, I would choose fermented black beans. Soy sauce is common to many Asian cuisines including Vietnamese, Thai and Japanese. Other ingredients such as chili paste or oyster sauce are also not unique to Chinese dishes. Fermented black beans, however, appear to be one of the few ingredients that remain in the Middle Kingdom should be on the shelf of every cook who makes Chinese food at home.
The beans themselves look like small black raisins. They should be resilient but not hard. They can be quite wrinkled although more pliable ones are likely to be fresher. The smell varies from smoky to cheesy and they always have a strong salty soy taste. I like Yang Jiang which is preserved with salt and ginger. Left covered in the cupboard, it keeps for months.
This food could be made at home, although few would do so. Susanna Foo, in her eponymous book Susanna Foo Chinese Cuisine, writes about a neighbour in Taiwan who made her own fermented black beans. She would mix black soybeans with salt, spices and gingerroot and let them sit out to ferment. She then sun-dried this concoction in her backyard for many days. During that time the whole neighbourhood acquired a pronounced smell, and my mother would complain that the odor was offensive.
Since these are soy beans, they are nutritious although they can be very salty. Some recipes recommend soaking them to remove the excess salt and then rising and using them. It may depend upon the brand. I usually add them, chopped coarsely, directly to a recipe, particularly in stir fries where they pair wonderfully with chopped garlic.
They also work well with chicken or fish. Try this dish: Use a whole cleaned sea bass or trout. Sprinkle the fish with a little salt and put it on a plate that will fit into a microwave oven. Grate an inch of ginger, chop a couple of garlic cloves and 2 tablespoons of fermented black beans. Shred two green onions or scallions. Mix these ingredients together and add 2 tablespoons of soy sauce and an equal amount of dry white wine or sherry and a teaspoon of sugar.
Let the fish marinate in this for a few minutes and then cover it with plastic wrapor leave it in the refrigerator until you are ready to cook. Set the dish in the microwave and cook it at the highest setting for about 10 minutesmore or less. It depends upon the thickness of the fish. If your microwave platter does not rotate, turn the fish after five minutes. When the flesh comes away from the bone, the fish is done.