1. In a large nonstick skillet, cook beef over medium-high heat, stirring occasionally, until no longer pink, about 5 minutes. Transfer meat to a colander and drain.
2. Using paper towels, wipe fat from skillet. Heat vegetable oil in skillet over medium-high heat. Add yellow onion, garlic, cumin, and red pepper; cook until onion is softened, about 5 minutes. Stir in beef; cook for 5 minutes.
3. Rinse lettuces and pat dry with paper towels. Tear into bite-size pieces; divide among 4 serving plates. Top with beef mixture. Sprinkle with red onion, tomatoes, chips, and cheddar. Top each salad with 2 tablespoons of salsa. In a small bowl, whisk together lime juice and olive oil. Drizzle over salads and serve.