Cut 2 large ripe avocados in half lengthwise and remove the pit.
Slice the flesh of the avocado intodice. It's safer to do this with a blunt knife.
With a spoon, scoopout the avocado from its shell and add it to a bowl.
Add 2 tablespoons fresh lime juice, ⅓ teaspoon salt, and mash the avocado with a fork. Don't over-mash it, some avocado bits are fine.
Add 3 tablespoons red onion (finely chopped), 2 tablespoons cilantro (finely chopped), and stir. Optionally you can add 1 ripe tomato (chopped) and 2 jalapeño or serrano chilis (chopped).Taste and adjust for salt and lime juice.