Cheddar and Horseradish Burger | Savor Recipes

Ingredients

• 1 pound 85% lean ground beef
• 2 tablespoons prepared horseradish
• 2 teaspoons Dijon mustard
• 1/2 teaspoon salt
• 1/4 teaspoon ground black pepper
• 4 (1/2-inch thick) slices red onion, not separated into rings
• 2 teaspoons olive oil
• 4 ounces sharp Cheddar cheese, sliced
• 4 large slices sourdough bread, cut in half
• Lettuce leaves