Melt butter in Dutch oven. Cook onions for 5 minutes. Add mushrooms and cook 5 minutes more. Stir in broth, paprika, soy and dill, reduce heat and simmer covered for 15 minutes. Whisk milk and flour and add to soup, straining to assure there are no lumps. Simmer for 15 minutes more. Stir in sour cream, parsley, lemon and seasoning. Heat through. Garnish with fresh parsley, croutons and sour cream.