Melt 1 tbsp. butter and 1 tbsp. olive oil in a large pot over medium heat. Saute the onions for 5 minutes. Add the mushrooms and saute for 5 more minutes. Remove with slotted spoon. Melt remaining 1 tbsp. butter. Stir in the flour, paprika, salt, and pepper and cook, stirring, for 1-2 minutes. Whisk in the chicken broth. Stir in soy sauce and cream. Return mushrooms and onions to the pan. Reduce heat to low, cover, and simmer for 15 minutes.
Stir in the dill and parsley. Serve with lemon and sour cream, if desired.