- In a large skillet, heat oil over medium-high heat. Add onions, and sauté 12 to 15 minutes, or until browned. Remove from heat, cover, and set aside.
- Preheat grill to medium-high heat.
- In a medium bowl, combine ground beef, ranch dressing, crushed tortilla chips, salt, and pepper; mix well. Divide the mixture into 4 equal amounts and make 4 patties. Grill patties 8 to 12 minutes, or until juices run clear, turning them over halfway through cooking.
- Place a slice of jalapeño cheese on each burger 2 minutes before removing burgers from the grill. When cheese is melted, remove burgers from grill, top each with a tomato slice and sautéed onions.