French Onion Soup

Ingredients

• 8 Yellow onion, halved and sliced thin
• 3 tbsp Unsalted butter
• 1 tbsp Extra-virgin olive oil
• 1 tsp Kosher salt
• ½ tsp Granulated sugar
• 2 tbsp All-purpose flour
• ¾ cup Dry white wine
• 6 cups Low-sodium vegetable broth
• 4 sprigs Fresh thyme
• 1 Bay leaves
• 1 tsp Balsamic vinegar
• 8 slices Baguette
• 5 oz Gruyère, grated

Method

1. Melt the butter with the oil in a wide heavy pot. Add all the onions with the salt and sugar — the pot will be alarmingly full — and cook covered over medium-low for 15 minutes to collapse them.
2. Uncover and cook 35-45 minutes more over medium-low, stirring every few minutes and scraping the brown film off the bottom each time. They should end up the color of dark caramel. This is the recipe; there is no fast version.
3. Stir in the flour and cook 2 minutes. Add the wine and let it reduce by half while you scrape the pot clean.
4. Add the broth, thyme and bay. Simmer 20 minutes. Fish out the herbs, add the vinegar, and taste for salt.
5. Toast the baguette slices until dry and hard.
6. Ladle the soup into oven-safe bowls, float two toasts on each, bury them in gruyère, and broil until the cheese is bubbling and browned in spots, 3-4 minutes.

Notes

✨ The restaurant touch

The brown film that keeps forming on the pot bottom is the flavor. Scraping it back into the onions each time is what builds the color that a good onion soup has.

🧒 For the kids

It is sweet, cheesy and comes with toast. Cool it well before serving — broiled soup holds heat far longer than it looks like it does.

🥡 Leftovers

The soup base keeps 4 days and freezes 3 months. Toast and cheese to order.

Per serving

Computed from USDA FoodData Central values. A planning tool, not medical advice.