Image by http://www.flickr.com/photos/veganfeast/

2 firm, but ripe, avocados
1/4 cup fresh lime juice
1 teaspoon salt
1/2 finely diced sweet onion
1 jalapeño, seeded and diced

1/2 cup seeded and diced ripe tomatoes

1/4 cup chopped fresh cilantro leaves (about 1/2 bunch)

Peel, pit, and quarter the avocados. In a bowl, mash together the avocados, lime juice, and salt using a heavy whisk or potato masher. Stir in the onion, jalapeño pepper, tomatoes, and cilantro. Use immediately, or, cover tightly, pressing plastic wrap directly on the surface of the guacamole and reserve in the refrigerator for up to 2 days.

From www.sweetonionsource.com.