Cook the onion, garlic and herbs
Peel the onion and garlic cloves and then finely chop them both. Place a pot over medium-high heat. Add the olive oil and butter. Leave the butter to melt, then add the chopped onion, garlic and chopped herbs. Cook for about 5 minutes on low heat.
cook the mushrooms
If you are using fresh mushrooms, clean them and cut on larger chunks. Add the mushrooms to the pot. Cook frozen sliced mushrooms for about 15 minutes and if you are using fresh mushrooms, cook them for about 5 minutes, stirring occasionally.TipWhen cooking the mushrooms it is super important they become beautifully golden brown. That color means that they are becoming caramelized, which means the soup will be full of flavor.
Cook the mushroom soup
Optionally add one tablespoon of white wine to the mushrooms, then pour in the vegetable stock or water. Season with salt and black pepper, then leave the mixture to boil. Once it starts to boil, reduce the heat and cook for about 10 minutes (low simmer).
Blend and serve
Remove the soup from the heat and blend it using an immersion blender (or in a blender). Season to taste with additional salt and pepper if necessary. In a separate small bowl stir to combine sour cream and 100 ml (1/2 cup) of water. Add the mixture to the mushroom soup, stir and serve. Divide the soup between four plates or bowls. Serve with pan-fried mushrooms, croutons, bread and/or fresh chopped parsley. Bon appetite.