When cooking French onion soup, a lot of the flavour comes from the caramelised onions, so it’s important not to rush this step. Take care to slice your onions very thinly, so they’ll combine effortlessly with the soup texture when serving. It may be tempting to cut the cooking time short for the onions, but they need it to properly caramelise and bring the signature richness and depth that French onion soup is renowned for.
With its complex flavours, this is a recipe that benefits from time in the fridge to let the flavours combine and deepen. It’s the perfect recipe to make on a Sunday for mouthwatering lunches to start the week and will taste even better on the second day of eating.
You can serve the soup as suggested in the recipe above, with a crunchy slice of cheesy baguette on top. Add a couple of extra baguette slices on the side to dip into the soup as you go.
We’ve shared a traditional French onion soup recipe above, but there are plenty of twists you can put on this dish. Chef Romain Avril shares his top tips in this elegant take on a French onion soup, using the flavours as inspiration for this refined recipe.
Choosing the right onions
Selecting the right variety of onions for this dish is a key step to making the best French onion soup. In the recipe above, we’ve suggested using yellow onions, as they have a high sugar content that’s well-suited to the caramelisation process. Avoid using white onions, as they’re too sharp in flavour and won’t develop the signature richness that you need for this dish. Explore over 20 different types of onions in our guide to choose your preferred variety.
Cheese and bread for gratin
For the topping, slices of crunchy baguettes are preferred for this dish. Gruyère is ideal for the cheese as it melts and bubbles into a golden, gooey layer. If you can’t source Gruyère at your local supermarket, try using Comté or aged Cheddar cheese instead.
How to store and reheat
French onion soup can be refrigerated for up to two days and will often taste better after time in the fridge. To reheat the soup, transfer it to a pan and warm it on the stove over a medium heat for around 10 minutes. Make the baguette slices fresh for the topping whilst the soup is warming through.
