20-30 minutes. Wash the cat's ear beans and boil them for 5 minutes, and then cook for 20 to 30 minutes. The toxins in them can be effectively removed. When making beans, you should be careful not to eat them before they are cooked, especially in When making cold beans, blanch the cat's ear beans for 20-30 minutes under the premise of ensuring safety. You must first cook them thoroughly and then cold them, so that it is safer.