French Onion Soup

A little overnight prep yields big results.

“Simmering onions in the slow cooker overnight makes them perfectly tender for this healthy version of the traditional soup,” says Oakland, California-based recipe developer Maren Ellingboe. And wild mushrooms are a great source of vitamin D for plant-based eaters.

Serves 6

Also in this series: Vegan Tomato Soup and Sweet Potato and Chickpea Curry


  • 2 tablespoons butter
  • 4 yellow onions, peeled and thinly sliced
  • ½ teaspoon salt
  • ½ teaspoon ground pepper
  • ¼ cup dried wild mushrooms
  • ½ cup white wine or sherry
  • 2 tablespoons soy sauce
  • 5 cups vegetable broth
  • 1 bay leaf
  • 1 teaspoon fresh thyme, chopped
  • 6 slices sourdough bread
  • 1 cup Gruyère cheese, shredded


  1. The night before you plan to serve the soup, add butter, onions, salt, and pepper to a slow cooker and toss to coat. Cook on low for 10 hours.

  2. Meanwhile, bring one cup of water to boil. Place mushrooms in a medium bowl and pour boiling water over. Let sit for 30 minutes. Pour mushrooms and water into a blender and puree until smooth. Refrigerate overnight.

  3. The next morning, add mushroom mixture, wine, soy sauce, vegetable broth, bay leaf and thyme to a slow cooker. Cook on high heat for four to five hours, or on low for eight to ten.

To Serve

  1. Preheat the broiler. Ladle soup into oven-safe bowls and place a slice of bread on each. Divide Gruyère cheese between bowls and place bowls on a rimmed baking sheet. Broil until cheese is melted, about three minutes. Serve immediately.