Gourmet Grilled Cheese! My Go-To Lunch Recipes - Food55

Ingredients

• 1 large yellow onion, thinly sliced (about 2 cups) (220g)
• 1 tablespoon olive oil (15 ml)
• 1 tablespoon unsalted butter (14g)
• 1/4 teaspoon salt (1.5g)
• 1/4 teaspoon black pepper (0.5g)
• 1 teaspoon brown sugar (4g)
• 1 tablespoon balsamic vinegar (15 ml)
• 2 slices sourdough bread (about 1/2 inch thick)
• 2 tablespoons unsalted butter, softened (28g)
• 3 ounces Gruyère cheese, shredded (about 3/4 cup) (85g)
• 2 tablespoons balsamic glaze (store-bought, or homemade) (30ml)