First cut off the feet of the crayfish, then turn around and remove the belly. When cutting the head, the incision should be as small as possible, so as not to let the yellow shrimp flow out, because the yellow shrimp tastes delicious, and then pull out the shrimp line. Then put it into a basin, add water, brush off the dirt on the crayfish with a brush, and rinse it for later use. At this time, ginger is minced, garlic is squashed and chopped into minced garlic, green pepper is pedicled, seeded and sliced, 200g rapeseed oil is poured into a pot to cook scallion oil, and scallion oil is cooked with rapeseed oil until the scallion oil is more fragrant. When the oil temperature is 50% hot, add green pepper, star anise, garlic, coriander and shallot in turn until all the ingredients are slightly burnt, and then take out the auxiliary materials, leaving only 50g scallion oil in the pot.