Soupe à l’Oignon (Onion Soup with Bread)

Some of the most richly flavored soups of all are onion. Some are purposefully pale, but deep flavor comes from gradual browning. Although many recipes call for sweet onions, a basic yellow onion is excellent if not better. More onions bring both more flavor and more sugar to the soup, the fuller flavor balancing the sweetness. Often there’s a little fl…