Heat the olive oil and butter in a large pot over medium heat. Add the sliced onions and cook, stirring frequently, until they are deeply caramelized. This takes about 25-30 minutes, but it’s worth every second. Add the garlic in the last minute of cooking.
Sear The Beef
Push the onions to the side of the pot and add the beef stew meat. Sear the pieces on all sides until browned. Sprinkle the flour over the beef and onions, stirring to coat everything evenly. Let this cook for another 2 minutes.
Add The Liquid
Pour in the beef broth and red wine (if using). Stir well to scrape up any bits stuck to the bottom of the pot. Add the thyme, bay leaf, salt, and pepper. Bring the soup to a boil, then reduce the heat to a gentle simmer. Cover and cook for about 45 minutes, or until the beef is tender.
Prepare The Toppings
While the soup is simmering, toast the baguette slices under a broiler until golden. Sprinkle grated Gruyère cheese on top and broil again until melted and bubbly.
Assemble And Serve
Remove the bay leaf from the soup. Ladle the hot soup into bowls, top each bowl with a cheesy baguette slice, and enjoy immediately.
Notes
This beef onion soup is a recipe I always turn to when I need something comforting yet elegant. The combination of caramelized onions and tender beef creates a flavor that feels both homey and luxurious. Don’t be afraid to make it your own by experimenting with herbs or cheeses.