Gourmet Patty Melts

Details

Ingredients

• 1 pound ground sirloin
• 1 tablespoon Worcestershire sauce
• 2 cloves garlic, minced, or more to taste
• ½ teaspoon salt
• ½ teaspoon ground black pepper
• 3 tablespoons unsalted butter
• 3 tablespoons olive oil
• 2 medium onions, sliced
• cooking spray
• 4 slices Cheddar cheese
• 4 teaspoons Dijon mustard
• 8 slices rye bread, lightly toasted