This rich, dark-brown soup is served with cheese-toast floating on top. It takes about an hour in total - about 15 minutes hands-on kitchen time. This recipe produces about two pints of soup.
Put a medium pan on the stove, and heat a generous splash of olive oil - a few dessert-spoonfuls. Chop the onions, and add them to the hot oil. If you have star-anise, add one 'spoke' (one seed) of that. Turn down the heat, and cook the onions slowly for about 20 minutes, stirring from time to time. The onions should be turning chestnut-coloured, but don't let them burn. The inside of the pan will get a coating of dark-brown caramel. Add finely-chopped garlic.
Once the onions are cooked, remove the star-anise if you added any. If you have some white wine, add a splash of wine to the pan, and use it to dissolve the caramel coating the inside. Then add about two pints of water. You can also add some stock, if you like - no more than one stock-cube. Add some salt and pepper. Bring the soup back to the boil, and then simmer for between half an hour and one hour. Check for seasoning and consistency. The soup should be dark brown, with a rich, sweetish, nutty flavour.
Cut the french bread into slices, smear the slices with oil on both sides, and toast them. Ladle the soup into bowls. Float a couple of slices of toast on each bowl, and cover the toast with grated Gruyere. Put the bowls under a heated grill, and grill until the cheese is melted and bubbling. Serve immediately (watch your fingers!)