When buying live mussels, choose fresh, fleshy and sturdy mussels. If you want to cook mussels on the same day, please ask the clerk to take them out of the shell for you and remove the dark oval stomach the size of an egg. The rest should be the rainbow tube. In this regard, the professional underwater fishermen's association advises not to eat the dark stomach or viscera of mussels. When preparing, cut the rainbow tube from the flesh of the body, and longitudinally split it in two holes at the thicker end. Then, with an extremely sharp knife, cut the rainbow tube obliquely into paper-like slices. After removing the soft part, the meat of the body can be sliced and served like a rainbow tube, or it can be chopped and put into a delicious thick soup. It should be reminded that mussels will soon harden after being cooked. Therefore, it is best to put the broth in a pot and cook it very quickly with boiling water, or throw it into the boiling sauce as quickly as possible.