Halve the Roma tomatoes vertically and use a spoon to remove the seeds and watery pulp to ensure a crisp, non-soggy consistency.

Dice the tomato flesh into uniform 1/4-inch cubes and place them into a non-reactive glass or stainless steel mixing bowl.

Finely dice the white onion and mince the serrano peppers, then add them to the bowl with the tomatoes.

Wash and thoroughly dry the cilantro before finely chopping; incorporate it into the vegetable mixture.

Drizzle the fresh lime juice over the ingredients and sprinkle evenly with sea salt and black pepper.

Fold the ingredients together gently with a spatula until the vegetables are evenly coated in lime juice and seasoning.

Allow the mixture to rest at room temperature for at least 15 to 20 minutes before serving; this allows the salt to draw out the tomato juices and mellow the sharp bite of the raw onion.