In a food processor, combine the onion and garlic. Pulse until they are finely chopped, releasing the aromatic fragrance.

Add the tomatoes and jalapeño to the processor. Pulse just a few times until they are slightly broken down but still chunky.

Add cilantro, lime juice, lime zest, salt, cumin, and sugar. Pulse to combine all ingredients into a chunky salsa consistency.

If the salsa is too watery due to the tomatoes, strain half of it to remove some liquid. Then, recombine it with the remaining salsa.

Taste the salsa and adjust the seasoning if necessary. Add more salt or lime juice to suit your preference. Enjoy immediately or refrigerate for later.