Ingredients
– 4 tablespoons unsalted butter
– 1 pound yellow or Vidalia onions (peeled, halved, and thinly sliced)
– Kosher salt (to taste)
– Black pepper (to taste)
– 2 teaspoons sherry, red-wine, or white-wine vinegar (optional)
– 4 ounces grated Gruyère cheese
– 4 slices of bread no wider than ½-inch thick
Notes
🧅 Caramelize onions ahead and freeze for quick gourmet sandwiches anytime.
🍷 Deglaze with sherry or bourbon for richer, more complex onion flavor.
🥪 Use thin bread slices and press while cooking for even melting and crisp edges.
- Prep Time: 10 minutes
- Cook Time: 35 minutes
- Category: Main Course
- Method: Stovetop
- Cuisine: French
- Diet: Vegetarian
Nutrition
- Serving Size: 1 sandwich
- Calories: 680 kcal
- Sugar: 15g
- Sodium: 874mg
- Fat: 44g
- Saturated Fat: 25g
- Unsaturated Fat: 19g
- Trans Fat: 0g
- Carbohydrates: 46g
- Fiber: 5g
- Protein: 25g
- Cholesterol: 120mg