Warm olive oil in a large skillet over medium heat. Add diced onion and sauté until translucent, about 5 minutes. Add chopped garlic and sauté 1 minute more. Transfer to a bowl and allow to cool. In a medium bowl, combine chopped tomatoes, onion mixture, fresh lime juice, chopped fresh cilantro (if desired), and chili powder, garlic powder, salt and pepper.
Dip smart: Choose a brand of chips that has no more than 150 calories per ounce (that's about 16 chips, depending on the brand) or 150 milligrams of sodium and has at least 2 grams of fiber. Also be sure the chips are trans fat-free and contain fewer than 8 grams of fat in total.