Ingredients:
Canola oil or nonstick grilling cooking spray, for oiling the grates
1 medium red onion, thinly sliced
Kosher salt and freshly ground black pepper
2 tablespoons ketchup
2 tablespoons yellow mustard
4 whole wheat English muffins, split
1 medium ripe tomato, cored and cut into 4 thick slices
1 pound 90-percent lean ground beef
2 ounces 50-percent reduced-fat sharp Cheddar, grated (about 1/2 cup)
Pickles, for serving, optional
- Heat a grill to medium-high direct heat and lightly oil the grates using a paper towel soaked in canola oil or nonstick grilling cooking spray.
- Spread a 16-inch-long piece of nonstick aluminum foil on a cutting board (or mist a piece of regular aluminum foil with nonstick cooking spray). Top with the onions, 1/4 teaspoon each salt and pepper and 1 tablespoon water. Bring two sides of the foil together, fold over twice to create a seal and then seal the remaining two ends. Put on the grill and cook for 12 minutes, flipping once. The onions should be tender with only a bit of charring. Carefully open the top of the foil to let all the steam out and continue to cook the onions, tossing, until browned and lightly charred, 3 minutes longer. Remove from the heat.
- While the onions cook, mix the ketchup and mustard together in a small bowl. Season with pepper and set aside.