Start to finish: 30 minutes
1 pound ground sirloin
1 pound ground chuck
1 tablespoon Worcestershire sauce
1 teaspoon Coleman's dry mustard
1 teaspoon kosher salt
1/2 teaspoon ground black pepper
2 tablespoons extra-virgin olive oil
1/4 cup (1/2 stick) melted butter
6 kaiser rolls, sliced
6 crisp butter or Boston lettuce leaves
6 slices purple or sweet onion, such as Vidalia
2 large tomatoes, cut into 6 slices
6 slices cooked bacon (optional)
Ketchup, mustard, mayonnaise (optional)
Heat a grill to high.
In a large bowl, combine the ground sirloin and ground chuck. Mix it together, being careful not to overwork the meat. Add the Worcestershire sauce, dry mustard, salt and pepper. Mix until just combined, then divide the mixture into 6 pieces. Gently shape each piece into a burger about 3/4 inch thick. Press your thumb gently into the center of each to form a depression.
Brush the patties lightly on both sides with the olive oil. Reduce the heat to medium, then add the burgers and grill until the meat no longer is pink, 8 to 10 minutes, turning once halfway through grilling time.
Meanwhile, brush butter over both sides of the rolls and grill until lightly toasted, about 2 to 3 minutes.
Serve the burgers immediately on the buttered rolls with a lettuce leaf, a slice of raw onion, tomato and a slice of bacon, if desired. Serve with traditional condiments on the side.
Per serving: 550 calories; 260 calories from fat (47 percent of total calories); 30 g fat (12 g saturated; 1 g trans fats); 110 mg cholesterol; 36 g carbohydrate; 3 g fiber; 4 g sugar; 35 g protein; 760 mg sodium.