Authentic Soupe à l’Oignon Recipe France, Europe

The first step when preparing this classic French soup is to caramelize the onions. Depending on the type of onions and the amount of heat, this step can take as long as a few hours before the onions reach the right consistency and color. Liquid — usually water or beef broth — is added when the onions have been fully caramelized, and once everything is brought to a heavy boil, the heat is turned down, and the soup is left to simmer. The broth can be thickened with flour, either before or after adding the liquid. The finished soup is divided between individual crock pots, and dry bread or toasted croutons are placed on top. For the gratinated version, a copious amount of grated cheese — preferably Gruyère or Comté — is placed over the bread, and the entire dish is placed under the broiler, melting the cheese and giving it a beautiful golden crust.