When the fish head is split in two, season with salt for at least 15 minutes. Fish heads should be fried in oil pan, preferably in large oil pan. After the fried fish head is taken out, stir-fry the ginger slices in another pot, add the fish head with boiling water and then add the tofu. After the water is boiled, simmer slowly until the soup turns white and salty. If it is not salty enough, add the right amount of salt. If you like pepper soup, you can add some white pepper. All right.