1. Heat a deep bottomed pan, add 2 cups of water.
2. Throw in the ginger, onion and tomatoes.
3. Bring everything to a boil and cover and simmer for 5 minutes.
4. Drop in the salmon and the shrimp.
5. Add the green chilies and season with patis.
6. Empty the tamarind powder mix and blend it in.
7. Add the camote tops, cover and simmer for 2 minutes.