The pot has been used for a long time. First of all, we spread a layer of flour on the bottom of the pot, and pay attention to the position with black slag to spread it a little thicker. Next, we pour out a part of white vinegar in the pot, so that the white vinegar can not exceed the height of the paste pot and flour. Then put the pot on the fire and add the white vinegar to boil. A small amount of white vinegar will soon corrode the black residue. Turn off the fire after boiling. Just let the wok stand 15 minutes and let the white vinegar soak the flour and stains in the wok, which will make them loose and even fall down by itself. Finally, take a scouring pad, rinse the bottom of the pan with water and wipe off the last stain, so that the wok can be restored as new.