The patient cook wins hands down when it comes to onion soup. Long, slow cooking brings out the onions' natural sweetness, and diligent stirring, every 15 minutes or so to ensure they don't burn, is of the utmost importance. It's probable that such attentiveness, a luxury of modern-day chefs, was not a common practice in bucolic France where the soup originates. The soup, something of a staple in rural households, was little more than water poured over stale bread crusts, the flavoursome bulb added and the whole lot left to simmer for the day. Onions, which grew in abundance and, more importantly, all year round, were the obvious choice for a nourishing meal.
It's unclear when the broth was wed to cheese to become soup a l'oignon gratinée but it's this version that has come to be referred to as French onion soup. Its popularity as the four am pick-me-up du jour for the butchers and purveyors who frequented the bistros around the legendary produce market, Les Halles in Paris, no doubt cemented the soup's reputation as a tonic. Although the market itself is gone, night revellers still seek out the restorative broth all around France. "After a big night out, you either go for a bowl of onion soup, the bakery or straight to bed," says owner of Sydney's La Brasserie, Philippe Valet.
Vigilance rules supreme when creating the sweet caramelised flavour that accents this perennial French favourite.