Exercise:

1. Wash the fish head and cut it in half. Cut tender tofu into chunks with a thickness of 1cm. Soak mushrooms in warm water for 5 minutes, then remove the pedicels and wash them.

2. Pour the oil into the frying pan. When it is 70% hot, put in the fish head and fry on both sides (about 3 minutes on each side) over medium heat. Put the fish head on one side of the pot, saute the onion and ginger slices with the oil in the pot, and pour enough boiling water into the fish head.

3. Add mushrooms, cover and stew for 50 minutes.

4. Add salt and lemon slices, add tofu and cook for 3 minutes.

Note: If you like more sour taste, cook for a few more minutes on low heat.