French Onion Soup

Melt the butter with the olive oil in a wide heavy pan over medium heat. Width matters more than depth here, because the water coming out of the onions has to evaporate rather than pool.

Add the onions, which will fill the pan almost to the rim.

Stir in the 5g of fine salt, which draws the water out and gets things moving.

Cook uncovered over medium-low heat for 45-60 minutes, stirring every 5 minutes and more often towards the end.

Keep the heat low enough that the onions never sizzle hard. This is the step that cannot be hurried and there is no honest shortcut — high heat scorches the sugars before the water has cooked out, and burnt onion is bitter in a way no amount of stock covers up. Fifty minutes is the real number.

Watch the colour go from pale to straw to deep mahogany, and the volume drop to roughly a quarter of what went into the pan. That collapse is the doneness cue, not the clock.

Scrape the brown film off the base back into the onions each time it builds up, adding a tablespoon of the wine if it starts to catch.

Pour in the wine.

Scrape the base of the pan clean with a wooden spoon while the wine bubbles. Everything stuck down there is the flavour you spent an hour making, and this is your one chance to get it back into the soup.

Simmer for 3-4 minutes, until the raw alcohol smell has gone.

Add the warmed stock, the bay leaves and the thyme. A batch of the chicken stock in this collection covers this pan with some to spare.

Simmer gently and uncovered for 20-25 minutes, until the broth has darkened and tastes of more than stock.

Fish out the bay leaves and thyme stalks.

Taste and add salt if it needs it, which depends entirely on how the stock was seasoned.

Heat the grill to high.

Toast the bread on both sides until it is dry and firm right through. Soft bread sinks and dissolves into the soup within a minute, and you lose the raft that holds the cheese.

Rub one side of each toast with the cut garlic clove.

Ladle the soup into four heatproof bowls.

Float a toast on each, garlic side up.

Pile the Gruyere over the toast and right out to the rim of the bowl, so it seals the surface.

Grill for 2-3 minutes, until the cheese is molten and blistered brown in patches.

Stand the bowls for 2 minutes before serving. Cheese straight from the grill is hot enough to burn.