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Delicious Instant Pot French Onion Soup topped with melted cheese.

Instant Pot French Onion Soup

A cozy and comforting Instant Pot French Onion Soup made with caramelized onions, rich broth, and topped with melted Gruyere cheese over toasted baguette.
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Prep Time 20 minutes
Cook Time 30 minutes
Total Time 50 minutes
Servings: 6 servings
Course: Appetizer, Soup
Cuisine: French
Calories: 320
Ingredients Method Notes

Ingredients
  

For the soup base
  • 6-8 large large yellow onions, thinly sliced (about 6 to 8 cups) Use sweet onions for a naturally sweeter result.
  • 3 tablespoons unsalted butter, or a mix of butter and olive oil for higher smoke tolerance
  • 1-2 teaspoons fine sea salt To coax moisture from the onions.
  • 1 teaspoon granulated sugar (optional) To accelerate caramelization if onions are not very sweet.
  • 1 teaspoon kosher salt Plus fresh black pepper to taste.
  • 3 cloves garlic, finely minced Fresh, not jarred.
  • 2 sprigs fresh thyme Or 1 teaspoon dried thyme.
  • 2 bay leaves bay leaves
Broth and seasoning
  • 6 cups low-sodium beef broth For a classic flavor; use low-sodium vegetable broth for a vegetarian option.
  • 1 cup water, reserved for deglazing Or additional broth.
  • 1 tablespoon low-sodium soy sauce or Worcestershire sauce (optional) For umami flavor.
  • 1 teaspoon balsamic vinegar or 1 tablespoon balsamic glaze (optional) For brightness.
For serving
  • 1 baguette baguette, cut into 1/2-inch slices and toasted until golden Day-old bread works beautifully.
  • 2-3 cups grated Gruyere cheese Or a mix of Gruyere and Swiss for a nuttier flavor; for dairy-free, use a melting plant-based alternative.
  • to taste fresh chopped parsley for garnish Optional.

Method
 

Preparation
  1. Peel and halve the onions, then slice them thinly from root to tip to achieve long strands.
Sauté the onions in the Instant Pot
  1. Turn the Instant Pot to Sauté mode, add butter and olive oil, and once hot, add onions and salt.
Encourage deep caramelization
  1. Once onions are soft and beginning to brown, add optional sugar and continue to sauté.
Add garlic and herbs
  1. Add minced garlic, thyme sprigs, and bay leaves. Sauté until fragrant.
Deglaze the pot
  1. Pour in hot water or some broth and scrape the bottom to loosen any bits.
Add the broth and seasonings
  1. Pour in remaining broth, add soy sauce or Worcestershire, and season lightly with black pepper.
Pressure cook
  1. Secure the lid, set valve to Sealing, and pressure cook on High for 5 minutes.
Natural release and flavor check
  1. Allow a natural pressure release for 10 minutes, then release remaining pressure. Taste and adjust seasoning.
Prepare the bread and cheese
  1. Toast baguette slices until golden and crisp, then prepare to broil.
Assemble and finish under the broiler
  1. Ladle soup into bowls, top with toasted baguette slices, and cover with grated cheese.
Serve right away
  1. Garnish with parsley and serve hot.

Notes

This soup is best served fresh, and leftovers can be stored in the fridge or frozen.