Stinky tofu is also known as the Imperial Green Square. The name was given to it because it was a favorite of the old Buddha.

The essence of making stinky tofu is the method of making the marinade. Cut the amaranth stalks into inch pieces, put them into a large pot, add water, and after a few days they will blister and become moldy, which is how the moldy amaranth stalks are made. The water left over from the moldy amaranth stalks is the mother liquor of the stinky brine. The green and a little bubbly water into a jar, throw a piece of tofu down, crushed, and wait for it to ferment and decompose to make the basic stink brine. The reason for putting a piece of tofu in is that there are only a few molds in the mother liquor, and the tofu provides a good source of raw material for these bacteria to multiply, and quickly. After a few pours, the urn is ready to be used. Wrap a few pieces of dried white tofu in Saran Wrap and put it in. After half a day in summer and two days in winter, the stinky tofu is ready. The main reason for using gauze is to prevent it from fermenting too much and becoming too crispy to fish out. But a pot of soup can't be made with just one shred of meat. It needs constant maintenance. It needs to be nourished by adding the soup from the veggie dishes to it every day after eating (commonly known as "to the foot of the bowl"). In addition, if it is not strong enough after a lot of stinking, just throw in another piece of tofu and mash it up. There are some unique methods such as putting crab lids or bamboo shoots into the fermentation, which is said to bring out the freshness. These are the experiences of those who have tried it themselves. The color of good stinky brine is light green and clear. I think it's because the bacteria in it have a strong ability to decompose, and the organic matter doesn't stay in it for long. (Actually, if it's wild amaranth, it's tasty enough without all this, but it's hard to find nowadays, so if you're in the countryside -- excluding Shanghai -- you might be able to find it.)

The surface of the dried tofu has a light green color after it has been soaked in the stinky brine, and it is crispy to the touch, because of the fermentation. The black or other colors of dried tofu are either due to a different process, or are specially made by unscrupulous merchants, and are rarely seen, at least in the south of the Yangtze River.