In a food processor, combine the whole tomatoes, chopped onion, cilantro, garlic, jalapeno, and salt.
Squeeze in the juice of half a lime and add the sugar if your canned tomatoes are unsweetened. If they already contain sugar, skip this step.
Pulse the mixture until you achieve your preferred consistency.
Taste the salsa and adjust with more lime juice or salt if needed.
For the best flavor, refrigerate the salsa overnight before serving.
