Roughly chop 4–5 medium Roma tomatoes and 1/4 medium white onion; remove the stem from 1 jalapeño (deseed for milder heat if desired) and peel 1 garlic clove.
Place chopped tomatoes, onion, jalapeño, garlic, 1/2 cup packed fresh cilantro leaves and tender stems, 1 tablespoon fresh lime juice, and 1/2 teaspoon salt into a food processor or blender.
Pulse the mixture in short bursts (about 5–10 times) until you reach your desired salsa consistency—chunky or slightly smoother.
Pour the salsa into a bowl, taste, and adjust salt or lime juice to your preference.
Serve immediately with tortilla chips or as a topping, or store leftovers in an airtight container in the refrigerator for up to 3–4 days.