1. Begin by preparing the soup base. Place a large non-stick pot over a low heat and add the vegetable oil and butter.

2. Peel and thinly slice the onions, keeping the root intact so they don’t fall apart as you do. You can carefully use a mandolin here but a sharp knife will also work fine. Once they are all sliced, get them into the pot with the two tablespoons of salt and mix. Cook this out over a low heat for 45-50 minutes, stirring with a wooden spoon every five minutes. Patience is required here.

3. Once the onions have reduced in size by more than half and are evenly golden brown, increase the heat to high.

4. Add your flour and cook out for a further minute before adding the white wine, followed by the stock a minute later. Bring the mix to the boil before reducing to a simmer. At this point, tie your thyme, bay leaves and rosemary together and add to the pot along with the rind from the Comté cheese. Simmer for 30 minutes.

5. While the soup simmers, preheat your grill to its highest setting. You can also lay out your ovenproof soup bowls and toast your sourdough slices in preparation.

6. After 30 minutes of simmering, adjust the seasoning with added salt and ground black pepper before removing the tied herbs and Comté rind and discarding. Carefully ladle the soup into the ovenproof bowls, filling almost to the top.

7. Using a cutter or a knife, cut the bread into circles of the same diameter as the bowls. Place on top of the soup and cover in a generous mound of finely grated Comté.

8. Place under the grill and gratinate for two minutes until dark golden brown. Allow to rest for five minutes before serving.