Soupe à l'Oignon Gratinée
This french onion soup recipe cooks a mountain of onions low and slow until they turn sweet and mahogany, simmers them in beef stock and white wine, then gratinées each bowl under a toasted baguette slice and melted Gruyère. One serving is one large bowl, about 512 g. It is the most famous soup in France, and the long caramelisation is what makes it.
Soupe à l'oignon gratinée is the soup of Paris bistros, though its roots reach back to Roman onion soups and to the markets of Les Halles, where workers ate it in the early hours. The modern gratinée version — beef stock, caramelised onions and a cap of bread and melted Gruyère — became the classic of late-night Paris, and it travelled with French cooking to become one of the most ordered soups in the world.
Pairs well with: Serve with a green salad and a glass of dry white wine; the salad's acidity balances the rich cheese.
Provenance
France
Paris Bistro Classic
Nordic & European
Time Dedication
1h 30m
20m prep • 70m cook
Batch Yield
4 Servings
536 kcal per serving
1 serving ≈ 512 g
Technical Skill
Intermediate
Intermediate (Slow Caramel)
Meal Timing & Digestive Fit
Breakfast
Not Advised
Lunch
Prime Metabolic Fit
Dinner
Ideal Hearty Main
Snack & Tea
Inappropriate
Paris Bistro Classic
Photo: Ralph Daily, CC BY 2.0, via Wikimedia Commons
The Heritage Formulary
Estimated cost: Low — about $3 per serving at home (USD)
Made with real beef stock, dry white wine and aged Gruyère, following the Paris bistro method of slow caramelisation and oven gratinée.
Execution Methodology & Culinary Technique
Prep Stage: Slice the Onions Evenly
20 Mins • Knife Work
Peel and slice all 900 g of onions thinly and evenly — uneven slices cook unevenly, and the pale ones stay raw while the thin ones burn. Grate the Gruyère, slice the baguette, and measure out the stock and wine so the long caramelisation is not interrupted.
Maestro Tip: A sharp knife and a steady rhythm matter more than speed: even 3 mm slices are the whole secret.
50 Mins Medium-low heat, about 150°C (300°F)
Melt the butter with the olive oil in a large, heavy pot over medium heat. Add the sliced onions and the sugar, stir to coat, and cook for 10 minutes until they soften and release their water. Then reduce the heat to medium-low and cook for 40–45 minutes, stirring every 5 minutes and scraping up the browned bits, until the onions are deep mahogany, sweet and jammy.
If the onions stick and darken too fast, add a splash of water and turn the heat down — patience is the whole dish.
Done when: Deep mahogany brown, sweet-smelling and jammy — not black or burnt.
4 Mins Medium heat, simmer about 95°C (203°F)
Add the garlic and thyme and cook for 1 minute until fragrant. Pour in the white wine and scrape the bottom of the pot — the wine lifts the caramelised sugars. Simmer for 3 minutes until the wine has mostly cooked off.
The wine is for deglazing, not for drinking later — let it reduce properly.
Done when: Wine reduced by two-thirds, pot bottom clean.
20 Mins Gentle simmer, about 95°C (203°F)
Pour in the beef stock and add the bay leaf. Bring to a gentle simmer, then cook uncovered for 20 minutes so the flavours come together. Taste and season with salt and pepper — remember the cheese and bread will add salt too. Remove and discard the bay leaf.
Season lightly now: the Gruyère and baguette add plenty of salt at the end.
Done when: Rich, savoury broth; onions meltingly soft.
6 Mins Oven 200°C (400°F)
While the soup simmers, heat the oven to 200°C (400°F) and toast the baguette slices on a baking tray for 5–6 minutes until golden and crisp on both sides. They must be dry enough to float on the soup without sinking.
Day-old bread toasts better; fresh bread stays soft in the middle.
Done when: Golden, crisp and dry through.
5 Mins Grill, about 230°C (450°F)
Heat the grill to high, about 230°C (450°F). Ladle the hot soup into 4 ovenproof bowls, float one toasted baguette slice on each, and pile the grated Gruyère generously over the bread. Place the bowls on a baking tray and grill for 3–5 minutes until the cheese is melted, bubbling and browned in spots.
Put the bowls on a tray — it catches drips and makes them safe to carry.
Done when: Cheese melted, bubbling and golden-brown in spots.
3 Mins Rest at room temperature
Rest the bowls for 3 minutes — the cheese and broth are scalding hot under the crust. Serve immediately, warning everyone to wait for the first spoonful.
A sprinkle of chopped parsley on top is traditional and adds colour.
Done when: Settled, still bubbling gently, safe to approach.
Finishing Touches & Plating
Serve the french onion soup gratinée bubbling hot in ovenproof bowls, with the cheese still blistering and a green salad on the side.
Nutritional Physiology & Benefits
Energy
536
kcal / serving
Protein
20g
Complete AA
Carbs
42g
Complex
Fats
30g
Healthy
| Energy | 536 kcal |
| Protein | 20 g |
| Carbohydrates | 42 g |
| Fat | 30 g |
| Fibre | 5.1 g |
| Sugar | 11.9 g |
| Sodium | 1267 mg |
| Energy | 105 kcal |
| Protein | 3.9 g |
| Carbohydrates | 8.2 g |
| Fat | 5.8 g |
| Fibre | 1 g |
| Sugar | 2.3 g |
| Sodium | 247 mg |
Nutrition values are estimated — calculated from USDA FoodData Central values for the listed ingredients.
Vitamins & minerals: Good source of vitamin C and vitamin B6 from the onions, with calcium and vitamin A from the Gruyère and butter.
Onions, Slowly Transformed
Nine hundred grams of onions cook down into the soup, bringing fibre and the sweet, savoury depth that defines the dish.
Protein and Slow Energy
Gruyère adds about 20 g of protein per bowl, and the baguette gives slow, steady energy.
Rich Broth, No Cream
The beef stock and thyme give the soup its mineral-rich, savoury base without any cream.
Food Pairings
To optimize nutrient absorption and elevate the sensory depth, pair with these authentic accompaniments:
Vegetables
Green Salad with Vinaigrette
A sharp vinaigrette on bitter leaves cuts through the rich Gruyère and resets the palate between spoonfuls.
Sides
Extra Baguette
Extra toasted baguette on the side is the practical tool for scooping up the last of the melted cheese.
Drinks
Dry White Wine
A dry white wine echoes the wine in the soup and lifts the sweetness of the onions.
Full Menus
With a Fruit Tart
A light fruit tart after the soup gives a sweet, fresh finish without another heavy course.
Complete menu
Serve the french onion soup with a green salad with a sharp vinaigrette, a glass of dry white wine, and a fruit tart to finish.
Digestive Guardrails
To prevent digestive distress, sluggishness, or palate clash, avoid pairing the dish with these elements:
Burning Hot Bowls
A gratinée bowl stays dangerously hot under the cheese crust — let it rest for 3 minutes and warn everyone at the table before they take the first spoonful. This is general guidance, not medical advice.
Rushed, Burnt Onions
Rushing the onions on high heat burns them bitter; the deep sweetness only comes from a slow, patient caramelisation. This is a cooking tip, not a health warning.
General information only, not medical advice — consult a doctor for personal dietary decisions.
Who Should Eat It
Health Conditions — Adjust or Avoid
If you have a medical condition, consult your doctor before changing your diet.
Storage & Use
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