Soak the dried porcini mushrooms in 1 cup/250ml of boiling water for 20 minutes.
Meanwhile melt the butter in a medium soup pot and sauté sliced celery, carrots and onion for 5-7 minutes over low heat until slightly softened, then add the minced garlic and thyme, continue cooking for half a minute longer.
Take the porcini mushrooms out of the liquid and strain the liquid, as there will be dry bits at the bottom. Chop the mushrooms and add to the pot together with the clarified soaking liquid.
Then add sliced chestnut mushrooms, wild rice and the vegetable stock, bring to a boil and cook for 30-35 minutes until the wild rice is cooked.
Pour in the heavy cream and stir to combine. Mix the melted butter with the flour in a small bowl, then add the mixture to the soup and stir until it’s dissolved. Add the chopped kale and continue cooking over low heat for about 5 minutes or until the broth thickens and the kale is cooked.
Notes
Using soy cream instead of double or heavy cream will make this a vegan recipe.