Top a plain burger with warm mushrooms and Swiss cheese for an easy but special burger.
1 tablespoon butter
8 ounces sliced fresh mushrooms
1 pound lean ground beef
1/4 cup Dijon-style mustard
4 hamburger buns
4 (1-ounce) slices Swiss cheese
Heat gas grill on medium or charcoal grill until coals are ash white.
Meanwhile, melt butter in 10-inch skillet until sizzling; add mushrooms. Cook over medium heat until mushrooms are lightly browned (5 to 8 minutes). Remove from heat. Keep warm.
Shape ground beef into 4 (3/4-inch thick) patties. Place patties on grill. Grill, turning once, until cooked through (15 to 18 minutes).
To serve, spread 1 tablespoon mustard on cut-sides of bun. Place 1 burger on bottom half of bun; top with 1/4 of the mushrooms, 1 slice cheese and top half of bun. Repeat with remaining ingredients.
Makes 4 servings.