Salsa Cruda

1 medium tomato
4 tablespoons finely chopped white onion
2 tablespoons chopped fresh coriander
3 Serrano chiles, with seeds, finely chopped
1/2 teaspoon salt, or to taste
1/3 cup cold water*

Chop the unskinned tomato and mix with the remaining ingredients.

* You may substitute fresh lime juice, if desired.