Classic French Onion Soup 🧅🧀

Classic French Onion Soup 🧅🧀

A bowl of French onion soup is the essence of Parisian comfort: sweet, slow-caramelized onions bathed in a savory, thyme-scented broth, capped with crisp baguette and a molten blanket of Gruyère. While its exact origins wind through 18th‑century France and the bustling Les Halles markets, the appeal is timeless—humble ingredients transformed by patience and heat. The magic lies in coaxing deep sweetness from onions and balancing it with wine, stock, and a whisper of Cognac.

History & cultural background

From Paris’s old Les Halles market stalls to modern bistros, this soup celebrates thrift and technique. Caramelizing draws out natural sugars, wine brightens the base, and stock adds savor—topped with toasted bread and Gruyère for that irresistible, bubbling gratin.

Ingredients

  • 1.2 kg yellow onions, thinly sliced 🧅
  • 3 tbsp (42 g) unsalted butter + 2 tbsp olive oil 🧈🫒
  • 1 1/2 tsp kosher salt, plus more to taste 🧂
  • Pinch of sugar (optional) ✨
  • 150 ml dry white wine 🍷
  • 1.5 L warm beef stock (or beef/chicken mix) 🍲
  • 3–4 sprigs fresh thyme + 1 bay leaf 🌿
  • 1 tbsp Cognac or brandy (optional) 🥃
  • Freshly ground black pepper ⚫️
  • 1 small baguette, sliced and toasted 🥖
  • 200–250 g Gruyère, grated (or Comté/Emmental) 🧀

Instructions

  1. Caramelize the onions

    • Melt butter with oil over medium heat.
    • Add onions, salt, and a pinch of sugar. Cook 35–45 minutes, stirring every few minutes, until deep golden and jammy. Adjust heat so they brown slowly without burning.
    • If browned bits collect on the pot, splash in water and scrape them up—flavor gold.

  2. Deglaze and build flavor

    • Stir in white wine; simmer 2–3 minutes to mellow the acidity and lift fond.
    • Add warm stock, thyme, and bay. Simmer gently 20–25 minutes; it should smell round and savory, not harsh.
    • Fish out thyme stems and bay. Stir in Cognac for a restaurant-style finish (optional). Season to taste.

  3. Toast, top, and melt

    • Ladle soup into broiler-safe bowls. Top each with a slice or two of toasted baguette.
    • Blanket with Gruyère. Broil 2–4 minutes until bubbling and well bronzed. Rest 1–2 minutes to avoid molten-lava tongues.

  4. Serve

    • Garnish with thyme leaves and black pepper. Serve with a crisp salad—and maybe a glass of the same white wine.

Chef Tips

  • Slow is everything: under-caramelized onions = flat flavor. Aim for deep gold with jammy edges.
  • No wine? Deglaze with a splash of vinegar (sherry or white wine vinegar) plus 1 tsp sugar to balance.
  • Stock matters: beef stock gives backbone; a 50/50 beef-chicken mix keeps it delicate.
  • Cheese choices: Gruyère is classic; Comté adds nuttiness; Emmental melts elastically.
  • Make-ahead: Soup keeps 4 days chilled. Reheat gently; broil with fresh toasts and cheese just before serving.

Fun facts 🧠

  • The gratinéed bread cap is called a “croute.” It insulates the soup and melts cheese beautifully.
  • Comté is a popular swap for Gruyère and lends a slightly nuttier edge.

Serving suggestions 🍽️🍷

  • Pair with a crisp green salad and Dijon vinaigrette.
  • Serve as a starter before steak‑frites or roast chicken.
  • Sip the same dry white wine you used to deglaze.
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