In a very large bowl combine tomatoes, garbanzo beans, cucumber, sweet pepper, cilantro, and onion; set aside.
For dressing, in a screw-top jar combine oil, vinegar, salt, garlic, and sugar. Cover and shake well. Season to taste with additional sugar, if desired. Pour dressing over vegetable mixture, tossing to coat. Cover and chill 4 to 24 hours.
Let vegetable mixture stand at room temperature about 15 minutes before serving. Serve alone or toss with mixed greens as a light entree. Serve with lemon wedges to squeeze over salad. Makes 8 to 10 side-dish servings.