ripe avocados • red onion, minced (about 1/2 cup) • serrano chilies, stems and seeds removed, minced • cilantro leaves, finely chopped • fresh lime or lemon juice • coarse salt • freshly grated black pepper • ripe tomato, seeds and pulp removed, chopped • to 3 Garlic, pressed (optional) • Garnish with red radishes or jicama. Serve with tortilla chips