Make the Broth

• Place the water, tomato, and onion in a large cooking pot. Add in the fish sauce and the tamarind mix. Start with one tablespoon and add more if you want it more sour.
• Let the broth boil.
• Add the salmon belly to the boiling broth and cook for five more minutes, or until the salmon belly changes its color.
• Add the spinach and turn off the heat. Serve hot.