This is now my 6 year old's favorite soup. It's full of umami goodness.
Melt 4 T unsalted butter in a large pot over medium heat. Saute 2 C chopped onions for 5 minutes then add 1 lb fresh sliced mushrooms and saute for another 5 minutes.
Stir in 2 t dried dill, 1 T paprika, 1 T (gluten free) soy sauce & 2 C (gluten free) vegetable or chicken broth.
Reduce heat to love, cover and simmer for 15 minutes.
In a bowl, whisk 1 C milk & 3 T cornstarch or arrowroot. Pour into soup and stir well. Cover and simmer for 15 minutes, stirring occasionally.
Stir in 1 t sea salt, 1/4 t pepper, 2 t lemon juice & 1/2 C sour cream. Mix well. Heat through, 3-5 minutes. Do not boil. Serve immediately.