Traditional French onion soup recipes call for slowly caramelizing sliced onions. In this speedy version, onions are caramelized under the broiler, which is also used to make accompanying Swiss cheese toasts.
1. Preheat broiler. Spray broiler tray with cooking spray. Spread onions on broiler tray. Drizzle with grapeseed oil, and sprinkle with salt and white pepper. Broil 10 minutes, stir, then broil 10 minutes more, or until onions begin to brown. Stir in garlic. Broil 2 minutes more. (Some onions will be slightly charred.)
2. Transfer onions to pot, and cover with broth and 2 cups water. Bring to boil, stir in thyme and vinegar, reduce heat to medium-low, and simmer 10 minutes.
3. Meanwhile, arrange baguette slices in single layer on broiler tray lined with foil. Drizzle with olive oil, and season with salt and pepper, if desired. Sprinkle each slice with 2 tsp. grated cheese. Broil 2 minutes, or until cheese has melted and toast begins to brown.
4. Ladle soup into 4 bowls. Float 3 toasts in each bowl.