Cut 2 large avocados in half lengthwise, remove the pit, and slice their flesh into squares with a paring knife.Scoop out the avocado from its shell with a spoon and add it to a bowl.
Add 2 tablespoons fresh lime juice and ½ teaspoon salt, then mash the avocado with a fork.Add 3 tablespoons red onion, 2 tablespoons cilantro, 1 ripe tomato, and 2 jalapeños, all chopped.Stir well, taste, and adjust for salt and lime juice.