Heat oil in large nonstick skillet over medium-high heat until hot. Add onion, jalapeño pepper, and garlic; cook and stir 3 to 4 minutes or until lightly browned. Remove. Heat same skillet over medium-high heat until hot. Place beef steaks in skillet; cook 1 to 2 minutes, turning once. Do not overcook. Season with salt. Serve in rolls with onion mixture and tomato. Makes 2 servings.