Traditional French Onion Soup

Caramelizing the Onions

1. To make the soup, start by slicing your onions. Try to slice them finely for perfect and quick caramelization.
2. Place a Dutch oven or a heavy-based pan on low heat and add the butter. 
3. When the butter melts, add the sliced onions to the pan. 
4. Gently cook the onions until nice and soft, stirring occasionally to avoid them burning. That usually takes around 15 minutes. 
5. When they are soft and translucent, turn the heat up to medium-high to start the caramelization.
6. Keep stirring the onions to avoid burning them and be patient at that stage. We need nice golden brown color on onions without burning them. Burnt onions will give a bitter taste and unpleasant look to the soup. If the onions aren't caramelized enough, the soup will lack the sweetness coming from the onions.

Building the Soup

1. When the onions are golden brown and release their sweetness, add the garlic and cook for another minute.
2. Use vermouth or sherry to deglaze the pan, and then add the flour.
3. Give it a good stir then deglaze the pan again with some of the beef stock to dissolve all the brown bits stuck to the surface.
4. Add the whole bacon, bay leaves, thyme, and black pepper along with some more of the beef stock. Only add just enough stock to make a thick soup. You can always add more later if it's too thick at the end of the cooking period. 
5. Bring it to a boil, turn the heat to low, and let it gently simmer for 45 minutes.

Garnishing the Soup and Serving

1. Preheat the grill to 200° C (390° F) and start preparing your garnish while the soup is cooking.
2. Thinly slice the baguette, rub them with garlic, and place them in the oven for a few minutes until lightly toasted.
3. When the soup is cooked, remove the whole bacon, bay leaves, and thyme stalks. Check the seasoning and add some salt if needed.
4. Ladle the soup in individual oven-proof bowls or ramekins.
5. Put a slice (or two!) of baguettes on top of the soup, top them with your cheese mixture, and place the ramekins in the oven.
6. Let them under the grill until the cheese is bubbly and slightly golden.
7. If you don’t have oven-proof individual bowls or ramekins, you can grill the cheesy baguettes separately on a tray and place them on soup ladled in bowls.