French Onion Soup is an all time classic and when done well will rival any other soup. I have a long affinity with French onion soup and can remember watching mum ladling big bowlfuls at the table on lazy Sunday afternoons.
Originating in Lyon, the key to any good onion soup is the stock. Whilst the stock from a pot-au-feu is preferred, substituting homemade chicken or light beef stock or very good quality shop bought stock still renders great results when in a hurry.
When in the depths of winter I choose light beef stock over chicken stock – affording the soup extra depth and richness, I then substitute the latter in the warmer months. A small amount of french mustard perks things up a little!
Some choose to add flour to the onions at the beginning of cooking to thicken the stock. I believe this is an unnecessary step, the soup is sufficiently thick without the addition of flour. Comté cheese is best for topping the crouton; however, parmesan works well.
French Onion Soup
120g Unsalted Butter
1.5 litres Light Beef Stock (or stock from a pot-au-feu)
1 1/2 tsp French Mustard
3 Thin Slices Rustic Bread (Crusts Removed)
200g Comté or Parmesan Cheese
1) Slice the onions thinly. Sweat the onions over a low heat in a large pot with the butter for 30-45 minutes until lightly coloured and soft.
2) Add the stock and bring the soup to a simmer. Continue to simmer for 20 minutes. Add the french mustard and stir. Season to taste. Remove from the heat and set aside or keep warm until ready to serve.
3) Preheat your grill on high. Lightly toast the slices of bread under the grill. Remove and cut each slice in half.
4) Ladle the warm soup into bowls. Top each bowl with a crouton and sprinkle the crouton with the cheese. Grind some black pepper over each bowl.
5) Place the bowls under the grill for 2-4 minutes until the cheese melts and turns golden (be careful not to burn).