Pig's trotters contain bone, meat, fat and skin, so they should be ironed first. When scalding, you should put the ingredients and cold water into the pot, so that the bloody smell inside the pig's trotters will flow out with the gradual increase of temperature, and the blood water and excess fat will be scalded off, so that the boiled soup will be fresh and not greasy. After scalding, use cold boiled water to wash away the oil stains on the surface slightly, and the effect will be better.