Ingredients:

The Hamburgers:

2 1/2 lbs. freshly ground chuck (use a slightly course grind),
Kosher salt and freshly ground pepper,
16 cheddar cheese slices (1/4-inch-thick),
8 hamburger buns,
8 leaves romaine lettuce,
Grilled Vidalia onions (see recipe below),
8 beefsteak tomato slices (1/4-inch-thick, about 2 tomatoes),
Horseradish mustard (1 cup Dijon mustard, 2 Tbl. finely grated fresh horseradish, or prepared horseradish, drained. Mix the mustart and the horseradish together in a small bowl; serve at room temperature.).

Directions:

Form the chuck into 8 burgers using your BurgerMate and season with salt and pepper on both sides. On the preheated grill, cook 3–4 minutes on each side until medium rare.

During the last minutes of cooking, top each burger with 2 slices of cheese, cover the grill, and let the cheese melt, about 1 minute. Split the buns and toast on the grill, cut side down, until golden.

Place a burger in each bun and top with lettuce, onions, tomato, and a dollop of horseradish mustard. Arrange on a platter.

Ingredients:

The Grilled Vidalia Onions:

2 Vidalia onions, sliced crosswise (1/2-inch-thick, do not separate into rings),
Olive oil for brushing,
Kosher salt and freshly ground pepper.

Directions:

Preheat a gas or charcoal grill to high.

Brush the onions with olive oil on both sides and season with salt and pepper.

Grill until golden brown, 3–4 minutes
on each side.