1. One canned mutton soup, rinse off the dust on the outside, and open it carefully.
2. Cut south tofu into even thick slices.
3. Heat a very small amount of oil in the wok, add the chopped green onion and stir fragrant.
4. Pour the mutton soup into a pot and bring it to a boil.
5. After adding tofu and boiling, change the heat to low, add salt and pepper.
6. Join the Longkou vermicelli and let the soup submerge.
7. When the vermicelli gradually softens, add MSG and top with chili oil.
8. Put a large bowl out of the pot and sprinkle with chopped green onion.