- 2 ½ lb. Vidalia onions, thinly sliced
- ¼ cup butter, melted
- 2 tsp sugar
- 2 tsp salt
- ½ tsp black pepper
- 6 fresh thyme sprigs, bundled with string
- 1 bay leaf
- 6 cups beef broth
- 2 Tbsp red wine vinegar
- 12 ½ inch slices of bakery baguette bread
- 1 ½ cups shredded Swiss cheese
- In a 6 qt slow cooker, stir together onions, butter, salt and pepper. Add in thyme and the bay leaf. Cover and cook on high for 6 hours.
- After cooking, remove the thyme bundle and bay leaf. Stir in broth and vinegar. Cover and cook on high for 1 hour.
- Preheat broiler with racks about 6” below heat. Place oven-proof bowls on a large-rimmed baking sheet. Fill the bowls with soup mixture, top with bread and cheese. Broil till melted and browned.