French Onion Soup

Carlene Thomas RDN
Carlene Thomas RDN
December 14, 2021
This hands-off French onion soup recipe uses the Anova Precision Oven to caramelize the onions with no risk of burning, cook the soup, toast the bread, and broil the cheese to a perfect golden brown. This well balanced soup is slightly lighter and more flavor-forward than the traditional version, which means you can eat it for lunch and not need to nap under your desk afterwards. Note: While this recipe shows how to prepare the soup to serve family-style, which we highly recommend, you can also portion it into individual ramekins before adding the toast.
Serves
4
Prep Time
00:25
Cook Time
01:28
French Onion Soup
5 (6)
490
Ingredients
1.75 lb
yellow onions, thinly sliced with a mandolin
2 Tbsp
unsalted butter, melted
1 Tbsp
granulated sugar
2 tsp
Worcestershire sauce
1 tsp
white wine vinegar, plus more for serving
2 Tbsp
all-purpose flour
4 cups
beef stock
2.5 tsp
kosher salt
Freshly ground black pepper
3 sprigs
fresh thyme
1
bay leaf
1
baguette, sliced into thin rounds
½ cup
grated Gruyère cheese
Steps

1. Preheat the Oven

Rack
Sous Vide Mode: Off
Steam: 100%
Temp: 325°F
Heat: Rear

2. Toss Onions with Butter

Combine the onions and butter in a large bowl. Toss well to combine.
Toss Onions with Butter

3. Transfer to Pan

Evenly distribute the onions in a single layer on a rimmed sheet pan lined with a silicone baking mat or parchment paper.
Transfer to Pan

4. Steam Onions

Rack
Transfer to the oven and cook until tender and just starting to brown, about 25 minutes. Remove from the oven.
Sous Vide Mode: Off
Steam: 100%
Temp: 325°F
Heat: Rear
00:25 Timer

5. Add Seasonings to Onions

Add the sugar, Worcestershire sauce, and vinegar to the onions. Toss to coat and spread back in an even layer.
Add Seasonings to Onions

6. Caramelize Onions

Rack
Return to the oven and cook, stirring halfway through, until deeply caramelized, about 35 minutes. Remove from the oven.
Caramelize Onions
Sous Vide Mode: Off
Steam: Off
Temp: 325°F
Heat: Rear
00:35 Timer

7. Adjust Oven for Soup

Rack
Sous Vide Mode: Off
Steam: Off
Temp: 375°F
Heat: Top

8. Add Flour

Sprinkle the onions with the flour and toss to combine.
Add Flour

9. Transfer to Pot

Transfer the onions to a Dutch oven or other large pot. Stir in the stock, salt, a grating of pepper, the thyme, and bay leaves.
Transfer to Pot

10. Cook Soup

Rack
Transfer to the oven and cook until flavorful and slightly reduced, 20 minutes. Remove from the oven.
Cook Soup
Sous Vide Mode: Off
Steam: Off
Temp: 375°F
Heat: Top
00:20 Timer

11. Toast Baguette

Rack
Spread the baguette slices out on a rimmed sheet pan. Transfer to the oven and toast for 3 minutes. Remove from the oven.
Sous Vide Mode: Off
Steam: Off
Temp: 375°F
Heat: Top
00:03 Timer

12. Add Toast to Soup

Cover the top of the soup with the toasted bread (see note).
Add Toast to Soup

13. Add Cheese

Cover the bread with the Gruyère.
Add Cheese

14. Broil

Rack
Return the pot to the oven and broil until the cheese is melted and bubbling, about 5 minutes.
Sous Vide Mode: Off
Steam: Off
Temp: 375°F
Heat: Top
00:05 Timer

15. Serve

Sprinkle with a splash of vinegar and serve immediately.
Serve
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