Only know one way:
Sauté ed mutton slices with onion
Slice the leg of lamb (if it is not easy to cut, put it in the refrigerator for a while), marinate it with starch cooking wine for a while, and then you can cut the onion. A little more scallion is better and delicious. Cut the onion into hob pieces. It's basically the same size as mutton slices. Put the oil in the pot, it is best to heat the pot and cool the oil, otherwise it will be easy to put it in the pot. Then stir-fry the meat slices quickly, slide them open, add soy sauce, sugar, salt and a little vinegar after discoloration (this will improve the taste, but don't overdo it, otherwise it will be very sour). Add the onion and stir fry a little. Put monosodium glutamate before cooking. The point of attention is to be quick, because the meat doesn't taste good when it is old. This method can also be used to fry onions and beef.