Roasted Garlic Onion Soup (Printable)

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

# Components:

→ 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

# Method:

01 - Preheat oven to 400°F. Slice tops off garlic heads, drizzle with 1 tablespoon olive oil, wrap tightly 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 25-30 minutes until onions are deeply caramelized and golden brown.
03 - Pour in white wine and scrape up all browned bits from pot bottom. Simmer until liquid reduces by half, approximately 5 minutes.
04 - Stir in roasted garlic, vegetable broth, soy sauce if using, thyme sprigs, bay leaf, and oregano. Bring to boil, then reduce heat and simmer uncovered for 25 minutes. Remove thyme sprigs and bay leaf.
05 - While soup simmers, toss bread cubes with 2 tablespoons olive oil, parsley, dried thyme, garlic powder, and salt. Spread on baking sheet and bake at 400°F for 10-12 minutes, stirring halfway through, until golden and crisp.
06 - Taste soup and adjust salt and pepper as needed. For smoother texture, use immersion blender to partially or fully puree soup.
07 - Ladle soup into bowls and top generously with herb croutons. Garnish with fresh parsley if desired.

# Expert Advice:

01 -
  • The roasted garlic becomes so silky and sweet that even garlic skeptics will ask for seconds.
  • One pot (mostly) means less cleanup and more time savoring what you've made.
  • Caramelized onions do the heavy lifting for flavor, so the soup tastes restaurant-quality without fussy techniques.
02 -
  • Don't rush the caramelization—those 25 to 30 minutes are non-negotiable if you want the deep, complex flavor that makes this soup sing.
  • Make the croutons on the same baking sheet as the garlic if your timing is right, or bake them separately—cold, soggy croutons ruin the whole experience.
03 -
  • If your onions stick or brown too quickly, add a splash of broth or water to loosen the pan and lower the heat slightly—you're aiming for gradual caramelization, not a race.
  • Make this soup a day ahead if you can; the flavors deepen and mellow overnight, making it taste even richer when you reheat and serve it.
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