Roasted Garlic Onion Soup (Print Version)

Comforting soup featuring slow-roasted garlic, caramelized onions, and aromatic herb croutons.

# What You’ll 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 and 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 and 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

# Step-by-Step:

01 - Preheat oven to 400°F. Slice the 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 reserve.
02 - Heat 1 tablespoon olive oil and butter in a large pot over medium-low heat. Add onions, leek, celery, and carrot. Cook, stirring frequently, for 25 to 30 minutes until onions are deeply caramelized and golden brown.
03 - Add white wine to the pot, scraping up browned bits from the bottom. Simmer until liquid is reduced by half.
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, parsley, thyme or Italian herbs, garlic powder, and salt. Spread on a baking sheet and bake at 400°F for 10 to 12 minutes, stirring halfway through, until golden and crisp.
06 - Taste soup and adjust seasoning with salt and pepper. For a smoother texture, 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 Tips:

01 -
  • The roasted garlic becomes sweet and buttery, nothing like raw garlic's sharp bite, making this soup deeply savory without any heat.
  • Those herb croutons stay crisp even when they hit the warm broth, giving you texture that doesn't disappear after five minutes.
  • It's vegetarian comfort that feels indulgent enough to serve at a proper dinner party, yet simple enough to make on a Tuesday night.
02 -
  • Don't skimp on the caramelizing time—those brown onion bits are where the deep, savory flavor lives, and rushing it leaves you with something that tastes thin and one-dimensional.
  • Roasted garlic is completely different from raw garlic, and tasting it raw from the clove before you add it to the broth will shock you with how sweet and mild it becomes.
  • The croutons are non-negotiable for texture, but they're also forgiving—you can make them hours ahead and store them in an airtight container.
03 -
  • Use a heavy-bottomed pot for caramelizing so the heat distributes evenly and your onions brown rather than steam or burn in hot spots.
  • Don't cover the pot while caramelizing—the steam that escapes is part of what concentrates the sweetness, and covering it traps moisture and keeps the onions from browning.
  • Taste as you go and remember that salt enhances the roasted garlic flavor, so you might need more seasoning than you expect.
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