2 tablespoons finely chopped cilantro
 1 1/2 tablespoons finely chopped white onion
 2 serrano chiles, finely chopped (seeds removed for mild)
 1 teaspoon salt, or to taste
 2 large ripe avocados
 1/2 finely chopped, unskinned tomatoes
 Combine the chopped cilantro, onion, chiles, and salt, and chop again
 until all ingredients are well blended together, then add chopped
 Mash avocados, leaving them a little lumpy.
 Combine avocados and previous ingredients.
 (1)  Serrano chiles are fairly hot; it may be wise to reserve some of
 the chopped chiles and add later if you decide you would like a hotter
 guacamole.  Discarding the seeds and membrane will reduce the heat.
 (2)  Lime juice squeezed over the top  of completed guacamole will
 help preserve the vibrant green color.
 (3)  Use Haas avocados if they are available.