Melt butter in a large pot over medium heat. Add onions and mushrooms, cook until soft and translucent.
Add stock, white wine, dill, thyme, paprika, Worcestershire, and salt. Bring to a boil, then simmer until liquid reduces.
Whisk flour into milk until smooth, then add to the soup. Cook until thickened.
Stir in sour cream and lemon juice over low heat until fully incorporated.
Divide into bowls, top with fresh parsley to serve.