Beef broth - 6 cups
Onion - 2 1/4 lb. (peeled, halved and thinly sliced)
Alcoholic dry cider - 1 1/2 cups
Butter - 5 oz (diced)
French baguette - 12 slices
Dijon mustard - 2 tbsp
Gruyere cheese - 5 oz (grated)
Thyme leaves to taste
Salt and ground black pepper to taste
Directions:
Melt butter in a large saucepan. Add onions and 1 1/2 teaspoons sea salt. Cook 30 minutes stirring.
Pour cider and simmer until reduced by half. Pour the broth and simmer for 10 minutes. Pepper to taste.
Preheat grill on high. Place bread on a baking tray and toast both sides until dried, but not browned. Spread with mustard and top with cheese, then grill until cheese browns.
Pour cooked soup in bowls and top with cheese toasts.