Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   1       medium       Tomato (6 ounces)
   4       tablespoon   Finely chopped white onion
   2       tablespoon   Roughly chopped fresh coriander
   3                    Chiles seranos, finely chopped, with seeds
     1/2   teaspoon     Salt, or to taste
     1/3   cup          Cold water

Preparation:

Chop the unskinned tomato and mix with the rest of the ingredients. Although this can be made up to three hours ahead, it is best made at almost the last minute, for it soon loses its crispness and the coriander it's sharp flavo