Grilled Caramelized Onion Burgers Recipe

Ingredients

• Caramelized Onion
• 1 tablespoon Land O Lakes® Butter
• 2 large (4 cups) yellow onions, sliced
• 1 teaspoon finely chopped fresh thyme leaves *
• 1 teaspoon white wine vinegar
• 1/4 teaspoon coarse ground pepper
• 1/8 teaspoon salt
• Burger
• 1 1/2 pounds lean ground beef
• 2 tablespoons stone-ground mustard
• 1/4 teaspoon salt
• 2 teaspoons coarse ground pepper
• 4 onion hamburger buns, split