Caramelized yellow onions combined with your favorite soup stock and topped with a thick slice of Gruyere cheese toast will make this one of your favorite all-time soups!
In large pot, heat canola oil over medium high heat.
Add onions and garlic. Reduce heat to medium low. Cover and cook for 15 minutes, stirring frequently, until onions are softened. They will release moisture and start looking limp and clear.
Remove lid, season with salt, pepper and thyme and continue to cook until onions turn golden brown and are caramelized. This can take from 45 min to 2 hours depending on how high you turn the heat and how sweet and caramelized you want your onions to taste. The lower and slower you cook (2 hours) the onions, the sweeter and darker the results. Stir and scrape up browned bits from bottom of pan frequently - the higher the heat the more often you'll need to do this. If brown bits are too stubborn, add a tablespoon of water, broth, beer, wine or wine vinegar to loosen them. Do not let anything turn black!
When onions are to your liking, sprinkle onions with flour, stir well and sauté for 1 minute. This will add a little body to your soup, but is optional.
Deglaze pan with red wine, scraping up all browned bits. Add broth, Worcestershire sauce, and bay leaves. Place lid on pot slightly askew and simmer for 15 minutes on low heat.
Taste and adjust seasoning as desired with additional salt and pepper.
Preheat broiler for 5 minutes. Arrange bread slices on baking sheet and top with grated cheese. Broil for 1- 3 minutes until cheese is bubbly and golden, watch carefully.
Ladle soup into bowls and top with cheese toast.
If using oven proof soup bowls, place bowls on baking sheet. Ladle soup into bowls. Top with toast slices and sprinkle cheese evenly over top.Place tray of bowls under broiler. Broil on low for 3-4 minutes or until cheese is bubbly and golden.
Carefully remove hot tray from oven, serve and enjoy.