Classic French Onion Soup

Ingredients

• 2 pounds Yellow Onions (peeled and thinly sliced)
• 4 tablespoons Unsalted Butter (cut into pieces)
• 1 tablespoon Olive Oil (extra virgin, prevents butter from burning)
• 1 teaspoon Granulated Sugar (helps speed caramelization and adds color)
• 1 tablespoon All-Purpose Flour (for light thickening)
• 0.5 cup Dry Sherry (traditional deglazing liquid; can substitute cognac or dry white wine)
• 3.5 cups Beef Stock (homemade gelatinous stock; store‑bought works in a pinch)
• 2 teaspoons Fresh Thyme Leaves (fresh preferred)
• 0.25 teaspoon Salt (large pinch; adjust to taste)
• 2 each French Baguette (cut on an angle into ¾‑inch thick slices)
• 4 ounces Gruyère Cheese (grated)
• 2 ounces Fontina Cheese (grated)
• 2 ounces Swiss Cheese (grated)

Instructions

1. Prepare the onions

   Peel the yellow onions, cut each in half top‑down, then slice into thin, uniform strips for even caramelization.

   Time: PT10M

2. Caramelize the onions

   Melt 4 Tbsp butter in the heavy pot over medium‑low heat, add the sliced onions, drizzle 1 Tbsp olive oil, sprinkle 1 tsp sugar, and cook, stirring occasionally, for about 1 hour until deep golden‑brown and sweet.

   Time: PT1H

3. Add flour for light thickening

   Sprinkle 1 Tbsp flour over the caramelized onions and stir for 2‑3 minutes until the flour loses its raw smell.

   Time: PT5M

4. Deglaze with sherry

   Pour ½ cup dry sherry into the pot, scraping the browned bits from the bottom with the wooden spoon; let simmer for 2 minutes.

   Time: PT5M

5. Add stock, thyme and season

   Stir in 3½ cups beef stock, 2 tsp fresh thyme leaves, and a large pinch of salt. Bring to a boil, then reduce heat to a gentle simmer and cook for 30 minutes.

   Time: PT35M

6. Prepare bowls and cheese topping

   Ladle the hot soup into oven‑safe bowls. Top each with a slice of toasted baguette and evenly distribute a total of 8 oz grated cheese mixture (Gruyère, Fontina, Swiss) – about 3 oz per bowl.

   Time: PT10M

7. Broil the cheese

   Preheat the broiler on high. Place the bowls on a rimmed baking sheet and broil for 3‑5 minutes, watching closely, until the cheese is melted, bubbly, and golden‑brown.

   Time: PT5M

   Temperature: Broiler high

8. Serve

   Allow the soup to sit for a minute, then serve hot, optionally with a fresh baguette on the side.

   Time: PT2M

Nutrition Facts

Calories

380

Protein

15 g

Carbohydrates

30 g

Fat

18 g

Fiber

4 g

Ingredient Substitutions

• Instead of Yellow Onions: Sweet onions, Vidalia onions
• Instead of Unsalted Butter: Margarine, olive oil
• Instead of Olive Oil: Vegetable oil
• Instead of Granulated Sugar: Honey (use less)
• Instead of All-Purpose Flour: Cornstarch (½ amount)
• Instead of Dry Sherry: Dry white wine, Cognac
• Instead of Beef Stock: Chicken stock, Vegetable stock
• Instead of Fresh Thyme Leaves: Dried thyme (⅓ amount)
• Instead of Salt: Sea salt
• Instead of French Baguette: Crusty Italian bread
• Instead of Gruyère Cheese: Swiss cheese
• Instead of Fontina Cheese: Mozzarella
• Instead of Swiss Cheese: Gruyère

Equipment Needed

• Heavy‑bottom enameled cast‑iron pot
• Wooden flat‑bottom spoon
• Ladle
• Cheese grater
• Chef’s knife
• Cutting board
• Measuring cups and spoons
• Rimmed baking sheet
• Broiler (oven)
• Oven‑safe soup bowls

Critical Steps — Do Not Skip

• Caramelizing the onions to a deep golden brown
• Scraping the browned fond after adding sherry
• Broiling the cheese until perfectly melted and browned

Chef Tips from the Video

• Use a gelatinous, homemade beef stock for maximum depth of flavor
• Add a splash of brandy with the sherry for extra complexity
• Finish each bowl with a fresh baguette slice for added texture

Troubleshooting

Storage

Refrigerator: Store soup (without bread and cheese) in an airtight container for up to 3 days.

Freezer: Freeze soup (without bread and cheese) in freezer‑safe bags for up to 2 months; thaw before reheating.

Room temperature: Do not leave at room temperature for more than 2 hours.

Make-Ahead Tips

• Prepare the soup base a day ahead and refrigerate; add fresh baguette and cheese just before broiling
• Grate cheeses in advance and store in a sealed container
• Freeze the soup without bread/cheese for longer storage

Frequently Asked Questions