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Wild Mushroom Caramelized Onion and Kale Soup

Wild mushroom caramelized onion and kale soup with deeply golden onions simmered into a savory broth, plus browned mushrooms and wilted kale. Made by caramelizing onions for 35–40 minutes, then simmering with porcini-soaking liquid for a rich, earthy finish.
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Prep Time 20 minutes
Cook Time 50 minutes
Total Time 1 hour 10 minutes
Servings: 6 servings
Course: Main Dish
Cuisine: American
Calories: 390
Ingredients Equipment Method Notes

Ingredients
  

Soup base
  • 1 lb mixed wild mushrooms Use shiitake, cremini, and oyster mushrooms; slice them for even browning.
  • 1 oz dried porcini mushrooms Soak, then strain and reserve the soaking liquid for extra mushroom depth.
  • 3 onions Thinly sliced for caramelization.
  • 4 cups kale Stems removed and chopped; add near the end so it wilts, not overcooks.
  • 6 cloves garlic Minced.
  • 6 cups beef or vegetable broth Choose beef for richer flavor or vegetable for vegetarian.
  • 0.5 cup dry sherry or white wine Used for deglazing to lift browned bits.
  • 3 tbsp butter Melted with olive oil for caramelizing onions.
  • 2 tbsp olive oil Helps prevent burning while onions cook slowly.
  • 1 tbsp fresh thyme Add during simmer for fresh herbal aroma.
  • 1 tbsp balsamic vinegar Adds tang and rounds out the mushroom flavor.
  • 0.25 parmesan shavings For serving; add to each bowl.
  • 1 tbsp truffle oil Optional but recommended for a finishing drizzle.
  • 0.25 salt and pepper To taste, for final seasoning.

Equipment

  • 1 Dutch oven

Method
 

Caramelize onions
  1. Melt butter with olive oil in a large heavy pot over medium heat, then add the thinly sliced onions and stir to coat.
  2. Cook onions 35–40 minutes, stirring occasionally, until deeply golden and caramelized, scraping any browned bits from the pot.
Brown mushrooms and build flavor
  1. Add minced garlic and sliced mixed wild mushrooms, then cook 8 minutes until the mushrooms are browned.
  2. Pour in the dry sherry (or white wine) to deglaze, then cook 2 minutes to reduce slightly.
Simmer with porcini and kale
  1. Drain the soaked porcini, then add them to the pot along with the strained soaking liquid.
  2. Add broth, fresh thyme, and balsamic vinegar, then simmer 15 minutes to meld the flavors.
  3. Add chopped kale and cook 5 minutes until wilted.
Season and serve
  1. Season with salt and pepper to taste, then ladle into bowls.
  2. Top with parmesan shavings and drizzle with truffle oil before serving.

Notes

Pro tip: caramelize the onions until they look deep mahogany, not just golden, for the soup’s signature richness. Store leftovers in the refrigerator up to 4 days; reheat gently to avoid overcooking the kale. Freeze is not recommended because the kale texture can soften after thawing. For a dairy-free swap, omit parmesan and use more thyme and a drizzle of olive oil instead (or a dairy-free “parm” topping if desired).