Brazilian Onion Salsa

From “Moosewood Restaurant Cooks at Home” by the Moosewood Collective.

1/2 cup coarsely chopped onions
1 or 2 fresh chiles, stemmed and seeded
1/3 cup fresh lemon and/or lime juice
2 garlic cloves, minced or pressed
1/4 cup fresh cilantro or parsley [or basil for a different flavor]
1/2 cup chopped fresh tomatoes
1 Tablespoon olive oil
1/4 teaspoon salt (or to taste)  

Whirl all ingredients together in a blender or food processor until smooth.The salsa keeps, refrigerated, for 3 or 4 days.