In a medium saucepan, saute onions in 2 tablespoons butter, stirring occasionally, until they are soft but not brown. Sprinkle lightly with salt and pepper. Add remaining butter, mushrooms, dill weed, paprikas, tamari, and chicken broth. Cover and simmer 15 minutes. Adjust seasoning if needed. Just before serving, whisk in sour cream (do not let it boil).