Roasted Garlic Onion Soup (Printable)

A comforting soup with slow-roasted garlic, caramelized onions, and crispy herb croutons.

# What You Need:

→ Vegetables

01 - 3 large yellow onions, thinly sliced
02 - 2 whole heads garlic
03 - 1 large leek, white and light green parts, sliced
04 - 1 celery stalk, diced
05 - 1 medium carrot, diced

→ Fats & Oils

06 - 4 tablespoons olive oil, divided
07 - 2 tablespoons unsalted butter

→ Liquids

08 - 1/2 cup dry white wine
09 - 5 cups vegetable broth
10 - 1 teaspoon soy sauce, optional

→ Herbs & Seasonings

11 - 2 sprigs fresh thyme
12 - 1 bay leaf
13 - 1/2 teaspoon dried oregano
14 - Salt and black pepper to taste

→ Herb Croutons

15 - 3 cups day-old baguette, cut into 3/4-inch cubes
16 - 2 tablespoons olive oil
17 - 1 tablespoon fresh parsley, chopped
18 - 1 teaspoon dried thyme or Italian herbs
19 - 1/4 teaspoon garlic powder
20 - Pinch of salt

# Directions:

01 - Preheat oven to 400°F. Slice tops off garlic heads, drizzle with 1 tablespoon olive oil, wrap in foil, and roast for 40 minutes until soft and golden. Cool slightly, then squeeze roasted garlic from skins and set aside.
02 - While garlic roasts, heat 1 tablespoon olive oil and butter in a large pot over medium-low heat. Add onions, leek, celery, and carrot. Cook, stirring frequently, until onions are deeply caramelized and golden brown, approximately 25 to 30 minutes.
03 - Pour white wine into the pot, scraping up all browned bits from the bottom. Simmer until liquid is reduced by half, approximately 5 minutes.
04 - Stir in roasted garlic, vegetable broth, soy sauce if using, thyme sprigs, bay leaf, and oregano. Bring to a boil, then reduce heat and simmer uncovered for 25 minutes. Remove thyme sprigs and bay leaf.
05 - Toss bread cubes with 2 tablespoons olive oil, fresh parsley, dried thyme or Italian herbs, garlic powder, and salt. Spread on a baking sheet and bake at 400°F for 10 to 12 minutes, turning once, until golden and crisp.
06 - Taste soup and adjust seasoning with salt and pepper. For a smoother consistency, blend part or all of the soup using an immersion blender.
07 - Ladle soup into bowls and top with a generous handful of herb croutons. Garnish with fresh parsley if desired.

# Expert Advice:

01 -
  • The garlic becomes soft and buttery rather than aggressive, which genuinely feels like a kitchen secret once you taste it.
  • Those croutons stay crispy even when they hit the hot soup, thanks to a trick with timing and the right bread.
  • One pot mostly handles itself while you attend to life, then the oven does the finishing work for you.
02 -
  • Don't skip the low-and-slow caramelization of onions—rushing this step by turning up the heat gives you softened onions, not caramelized ones, and that's the entire soul of the soup.
  • Day-old bread for croutons isn't just a suggestion; fresh bread will turn into bread pudding in your soup rather than staying crisp.
03 -
  • Use a large, heavy-bottomed pot for the caramelization—it distributes heat evenly and prevents hot spots that would turn onions into charcoal.
  • If you're making this for guests, roast the garlic and caramelize the onions earlier in the day, then finish the soup just before serving so the croutons stay crunchy.
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