Heat the oil in a large nonstick skillet over medium heat. Add onion, garlic, and jalapeño; cover and cook 3 minutes or until onion is tender. Add tomatoes; bring to a boil. Reduce heat, and simmer, uncovered, 5 minutes. Cool completely. Stir in 2 tablespoons cilantro, pepper sauce, and sour cream. Cover and chill. Sprinkle with the remaining 1 tablespoon cilantro.