Method：

1. Rinse tofu and cut into small pieces.
2. Rinse tomatoes and dice.
3. Rinse the grass carp's tail and remove the scales, pat dry and marinate with salt.
4. Heat oil, sauté ginger and pan fry grass carp's tail until golden brown.
5. Bring water to boil, add grass carp's tail and cook over high heat, then turn to medium heat and cook for 20 minutes.
6. Add tomatoes, tofu and cook for 5 minutes.
7. Season with salt and pepper.