Melt the butter in a saucepan. Add the mushrooms and cook until they start to brown. Then add the scallions/spring onions, paprika and dill. Sautè for a few minutes.

Add the broth and soy sauce and bring to a simmer. Simmer on low for several minutes. While this is simmering, mix the flour and milk and work out all the lumps.

Add the milk mixture to the saucepan and cook it on a high simmer until the flour is cooked. Add the salt and pepper with the lemon juice and parsley. Cook for a few minutes on a low simmer and then adjust the seasonings if need be.

Just before serving add the sour cream and cook on a low simmer until it's heated through.

Serve in bowls with a dollop of sour cream and garnish with fresh parsley.