Cooking times are for fresh or thoroughly thawed ground beef. Ground beef should be cooked to an internal temperature of 160°F. Color is not a reliable indicator of ground beef doneness.
- 1 Pound ground beef (93% lean or leaner)
- 4 slices sweet onion (1/2 inch)
- 4 slices Swiss cheese
- 1/4 Cup mayonnaise
- 1 Tablespoon Dijon-style mustard
- 4 crusty rolls, split, toasted
- Romaine lettuce, tomato slices (optional)
Lightly shape ground beef into four 3/4-inch thick patties.
Coat onion with cooking spray.
Place patties on grid over medium, ash-covered coals; arrange onion around patties.
Grill, covered, 8 to 10 minutes (over medium heat on preheated gas grill, covered, 7 to 9 minutes) until instant-read thermometer inserted horizontally into center registers 160°F, turning occasionally.
Season with salt and pepper after turning, as desired.
About 1 minute before patties are done, top each with cheese.
Combine mayonnaise and mustard; spread on top and bottom halves of rolls.
Serve burgers and onion in rolls with lettuce and tomato, as desired.