For the mushroom sauce, clean the chanterelles, wash them and cut them wafer-thin. Peel the onions, chop finely and fry in half of the butter.
Add the mushrooms and sauté until soft. Heat the remaining butter, add 40 g flour and roast until golden.
Pour in cold water and stir until smooth. Add to the chanterelles, cook well and season with salt and pepper.
Mix sour cream with the remaining flour and stir into the sauce. Wash and chop the parsley. Serve the mushroom sauce sprinkled with parsley.