Roasted French Onion Soup with Vegetable Stock
A refined French onion soup that departs from the traditional Gratin tradition by building a rich vegetable stock base before caramelizing Spanish onions in the oven. Roasting concentrates the onion sugars while the aromatic stock infuses depth from mushrooms, garlic, and herbs. The addition of soy sauce adds umami complexity. Serve in deep bowls with crusty bread for a restaurant-quality first course or light supper. This version prioritizes the onion as the star, supported by a sophisticated broth rather than beef stock.
Ingredients
- 1 tablespoon vegetable oil
- 1 large onion, chopped coarsely
- 12 cloves garlic, separated and smashed
- 12 cups water
- 2 medium carrot, peeled and chopped
- 1 large potato, chopped
- 2 ribs celery, chopped
- 2 medium portabella mushroom, choppedcremini mushroom1:1substitution
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- 2 whole bay leaf
- ¼ teaspoon black peppercorn, whole
- ½ teaspoon salt
- 6 whole clove
- 4 large Spanish onion
- 12 cloves garlic, crushed
- 1 teaspoon salt
- 2 tablespoons olive oil
- 4 whole bay leaf
- 1 teaspoon thyme, dried
- 1 cup white wine, dry
- 2 tablespoons soy sauce
- salt, to taste
- black pepper, freshly ground, to taste
Instructions
- 1
Heat vegetable oil in a large soup pot over medium heat.
- 2
Add coarsely chopped onion and smashed garlic cloves, saute until lightly browned.
- 3
Add water, chopped carrots, potato, celery, mushrooms, bay leaves, black peppercorns, salt, and whole cloves.
- 4
Cover and bring to a boil, then reduce heat and simmer until vegetables are very soft.
- 5
Strain through a colander or sieve and reserve stock.
- 6
Preheat oven to 375°F.
- 7
In two shallow nonreactive baking pans, combine Spanish onions, crushed garlic, salt, olive oil, bay leaves, and thyme.
- 8
Roast, stirring every 15 minutes, until onions soften and lightly brown, covering with foil if browning too quickly.
- 9
Remove from oven and add wine to pans, stirring well to deglaze.
- 10
Transfer roasted onions and wine to the reserved stock.
- 11
Add soy sauce, cover, and bring to a boil.
- 12
Reduce heat and simmer, then taste and adjust salt and pepper.
- 13
Discard bay leaves before serving.
Tips
Stir roasted onions every 15 minutes to ensure even caramelization and prevent burning on edges.
Deglaze the roasting pans thoroughly with wine to capture browned bits that add depth to the final soup.
Use a nonreactive baking pan to prevent the acidic wine and stock from reacting with aluminum or cast iron.
Good to Know
Refrigerate in airtight container up to 4 days. Reheat gently on stovetop over medium-low heat, stirring occasionally.
Make stock base 2 days ahead. Roast onions up to 1 day ahead and combine just before serving for best texture.
Ladle into deep bowls. Accompany with thick slices of toasted baguette or crusty bread. Optional: top with grated Gruyere or Emmental and broil briefly.
Common Mistakes
Do not skip the colander straining to avoid vegetable debris clouding the final broth.
Do not neglect to stir roasted onions every 15 minutes to avoid uneven browning or scorching.
Do not discard bay leaves before straining the final soup to avoid missing them in bowls.
Substitutions
Gluten-Free Swaps
General Alternatives
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FAQ
Can I make this ahead of time?
Yes. The vegetable stock keeps refrigerated for 4 days. Roast onions separately and combine when ready to serve for optimal texture. Entire soup stores 3-4 days refrigerated. Freeze stock alone up to 3 months.
What if my onions are browning too quickly?
Cover the roasting pans with foil as directed in the recipe. Lower oven temperature by 10C if browning accelerates beyond 50 minutes. Stir more frequently to redistribute heat.
Can I use beef stock instead of vegetable stock?
Yes, beef stock creates a richer, more traditional French onion soup. Use equal volume of beef broth. Reduce or omit soy sauce since beef stock already carries deeper savory notes.