In a hot pan, fry the mushrooms, the bacon and a little oil to become golden. If necessary during cooking, drain the water excess and reserve. Once cooked, reserve the mushrooms.
In the same skillet over high fire, add the remaining oil, fry the kidneys ten minutes . Deglaze with the white wine and reduce to near dryness. Add the mustard, tarragon and sour cream. Stir. Add the mushrooms and their water. Simmer for a few minutes.
Adjust seasoning, add chives and serve with fried potatoes and fresh asparagus.