Melt the butter in a large saucepan over medium heat, add the onion and mushrooms and cook until the mushrooms have released their liquids and it has evaporated, about 10-15 minutes.
Mix in the flour and paprika and let it cook for 2-3 minutes.
Add the broth, dill, soy sauce, bring to a boil, reduce the heat and simmer for 10 minutes
Add the sour cream and lemon juice, and season with salt and pepper before adding the dill.
