Gourmet French Onion Soup

Real French onion soup lives and dies by how well you caramelize the onions. This recipe gives them the full treatment: 15 minutes covered and sweating in butter, then another 30 to 40 minutes uncovered at higher heat until they’re a deep, even golden brown.

A pinch of sugar helps the caramelization along, but the patience is what actually gets you there. Rushing this step with too much heat gives you burnt, bitter onions instead of sweet, jammy ones. Once the onions are properly browned, flour goes in for body, then boiling brown stock, dry white wine, and a generous splash of Cognac right before serving.

The Cognac is stirred in at the very end, off heat. Cooking it out would waste its aroma. You want that hit of warm, boozy fragrance rising from the bowl when it reaches the table.

Pro Tips

• Slice the onions thin and even. Thick pieces won’t caramelize properly in the same timeframe as thin ones.
• Stir frequently during the uncovered browning stage. The fond builds up fast on the bottom and burns if you walk away.
• Use toasted bread rounds, not soft bread. Soft bread dissolves into the broth instantly and you lose the whole point of the cheese-topped crust.
• Pile the Swiss cheese generously. It should melt into a thick, golden cap over the bread.

Variations

• Use Gruyere instead of Swiss for a nuttier, more complex cheese crust.
• Add a bay leaf and a sprig of thyme to the broth while it simmers for herbal depth.
• Swap Cognac for brandy if that’s what you have on hand.