Caramelized Onion and Beef Patty Sandwich

Ingredients

• 1 red onion, julienne sliced
• 1 teaspoon vegetable oil
• 1 ounce - butter
• 1 teaspoon sugar
• salt
• 3.5 ounces of ground beef, shaped into a patty
• 1 cheddar cheese
• 1 tablespoon bearnaise sauce
• 1 lettuce leaf
• 2 breads slices, toasted
• 1 radish, slices
• broccoli sprouts
• ½ teaspoon balsamic vinegar