Wash cilantro and serrano peppers, trim stems and discard.
Chop cilantro, serrano pepper, garlic and onion into small dice.
Place the cilantro, serrano peppers, garlic, onion and lime juice in a food processor or blender.
Pulse until all ingredients are finely chopped and combined.
Add the tomatoes to the mixture and pulse again until everything is well blended.
Add salt to taste and pulse one last time to combine ingredients thoroughly.
Serve chilled with chips or as a topping for tacos, burritos, enchiladas or your favorite Mexican dish!