- Portion size 4 servings
MethodCaramelized Onions: In skillet, heat oil over medium-low heat; cook onion, sugar, vinegar, salt, pepper and cumin seeds, stirring occasionally, until caramelized, about 20 minutes.
Meanwhile, spread butter over 1 side of each slice of bread; lay 4 slices, butter side down, on work surface. Spread evenly with mustard. Divide cheese slices evenly over bread. Top with onions and remaining bread, butter side up. Grill in skillet over medium heat, pressing with spatula or weight and flipping once, or in pancake griddle or panini press, until bread is crisp and browned and cheese is melted.