Wipe mushrooms with a damp cloth. Slice thinly.

Heat up a pot and add 4 tbsps butter. Add sliced mushrooms and cook until golden brown. This will take about 25 minutes. Stir occasionally.

Add chopped onion and a pinch of salt. Stir and cook until onions are soft, not golden brown. Add another tbsp butter if necessary. Make space in the center of the pot and add garlic. Stir and cook for a few seconds, mix into the mushrooms and cook about 30 seconds until raw flavor goes away.

Add thyme, paprika and bay leaf. Stir and cook for 10 seconds. Add flour, stir and cook for 2 minutes. Add soy sauce and chicken stock. Stir well and bring to a boil. Turn down to a simmer, cover pot and cook for 30 minutes.

Taste and adjust salt. Add ground black pepper and fresh lemon juice. Turn off heat. If adding sour cream, take some of the soup liquid and pour into a cup. Mix in sour cream until smooth and add to pot. Use a few tablespoons or up to a 1/4 cup of sour cream depending on your taste (You may substitute half and half or heavy cream for the sour cream). Stir well and serve hot. Garnish with chopped parsley if you wish.