Place the fresh tomatoes, onion, garlic, peppers, cilantro, lime juice, 2 teaspoons cumin, 2 teaspoons sugar (if using), and salt in a food processor. Pulse until the contents are fine and well blended.
Pour in the crushed tomatoes and green chiles. Puree until mostly smooth. Taste, then add more cumin and sugar if desired. Refrigerate until ready to serve.
