The Secret to Perfect French Onion Soup Lies in Slow Caramelisation

French onion soup remains a beloved comfort dish, especially on cold days. The recipe, though classic, doesn't appear in many traditional French bistro cookbooks—its origins stay unclear. For one writer, the first taste came at eight years old in Paris, sparked by a childhood fascination with the Asterix comics.

The soup starts with 100g of butter melted in a large pot over medium heat. Four large onions cook slowly until soft and caramelised, filling the kitchen with a rich, sweet smell.

Once the onions are ready, the pot is deglazed with 5cl of balsamic vinegar and 5cl of port wine or Marsala. Diced bacon, 1.2 litres of dark chicken or beef stock, and a bouquet garni are stirred in. The mixture simmers for 45 minutes to an hour, letting the flavours deepen.

To serve, the soup is ladled into ovenproof bowls. Toasted baguette slices and 250g of grated Gruyère cheese are placed on top. The bowls go under the grill until the cheese bubbles and turns golden. The dish arrives steaming, ready to warm anyone at the table.

Anthony Bourdain's The Les Halles Cookbook includes a version of this recipe. His take keeps the process simple but precise, just like the bistro-style original.

This hearty soup stays a staple in French cuisine, even without a clear history in old cookbooks. The mix of caramelised onions, rich stock, and melted cheese makes it a filling meal. It's best enjoyed fresh from the oven, offering warmth and comfort with every spoonful.