French Onion Soup (Soupe à l'Oignon Gratinée)

Soupe à l'oignon is among the most ancient preparations of the French repertoire — a frugal, sustaining soup of peasant origin elevated by patience and technique into something worthy of any table. The gratinéed version with its signature cheese and crouton crown was the speciality of Les Halles, the central Paris market that operated from medieval times until 1969 — the soup that sustained market workers through cold early-morning hours.

A long-caramelised onion soup, the onions cooked over low heat for 45 minutes minimum until they have reduced from a full pot to a sweet, mahogany-coloured tangle — deglazed with white wine and enriched with beef stock, ladled into an oven-safe soup bowl, topped with a slice of dried baguette and a generous cap of grated Gruyère and Comté, then gratinéed until the cheese is deep golden and bubbling over the edge of the bowl. French onion soup's character is entirely in the caramelisation time of the onions: 20 minutes produces a good onion soup; 45 minutes produces the correct one.