• 4 tablespoons butter
• 1 teaspoon salt
• 2 large red onions, thinly sliced
• 2 large sweet onions, thinly sliced
• 1 (48 fl. oz.) can chicken broth
• 1 (14 fl. Oz.) can beef broth
• ½ cup red wine
• 1 tablespoon Worcestershire sauce
• 2 sprigs fresh parsley
• 1 sprig fresh thyme leaves
• 1 bay leaf
• 1 tablespoon balsamic vinegar
• 1 pinch salt and freshy ground pepper
• 4 thick slices of French bread
• 8 sliced Gruyere or Swiss chese
• ½ cup shredded asiago or mozzarella cheese
• 4 pinches paprika
1) Melt butter in large pot over medium-high heat. Mix in salt, red onions and sweet onions. Cook 35 minutes with frequent stirring until onions are caramelized and syrupy.
2) Mix in chicken broth, beef broth, red wine, and Worcestershire sauce into pot. Bundle herbs: parsley, thyme and bay leaf and gently place into pot. Simmer over medium heat for 20 minutes, stirring occasionally.
3) Remove and discard herbs, reduce heat to low, and mix in vinegar, salt, and pepper. Cover and keep on low heat.
4) Preheat oven broiler. Place bread slices on baking sheet and broil 3 minutes, turning once, until well toasted.
5) Fill soup bowls with soup and submerge bread halfway. Garnish with Gruyere cheese, asiago, and paprika.