Core the tomatoes and cut into small, even dice - about 1/4 inch. Roma tomatoes hold their shape best. If your tomatoes are very juicy, scoop out some seeds and excess liquid with your fingers to prevent watery salsa.

Finely dice the onion - smaller than the tomato pieces so it distributes evenly. Mince the jalapeno, removing seeds and white pith for mild heat or keeping some seeds for medium. Mince the garlic and chop the cilantro, including tender stems.

In a large bowl, combine the diced tomatoes, onion, jalapeno, garlic, and cilantro. Squeeze fresh lime juice directly over the top - about 2 tablespoons. Sprinkle with salt and cumin if using.

Fold everything together gently with a spoon. Taste and adjust salt or lime as needed - the salt should make the flavors pop without tasting salty. Let sit at room temperature for 10 minutes so the salt can draw out the tomato juices and the flavors meld.

Taste again after resting - the flavors will have deepened. Adjust seasoning if needed. Serve immediately with tortilla chips, or refrigerate for up to 3 days. The salsa will get juicier as it sits.