Soak in water for a day, then shake off the impurities on the hairy belly, spread it on the chopping board, spread the belly leaves layer by layer, then wash the black film and grass smell repeatedly with clear water, cut off the edge of the belly door, tear off the oil skin at the bottom (the side without the belly leaves), cut off a big leaf and a small leaf as a whole, cut along the grain, and then straighten each leaf and cut it into about 1