Saure Nierndln (Sour Kidneys)

Water the kidneys in cold water for approximately 30 minutes. Take them out, dry, cut into approximately 5mm thick slices. Finely dice the onions. Heat up 4 tbsp. oil in a pan, fry onions light-brown, dust with a bit of flour. Add soup, boil for approximately 4 minutes. Heat up the remaining oil in a separate frying pan and fry the kidneys until just brown. Combine kidneys and onions, hot but not too hot, salt and pepper. Season to taste with vinegar. Add thoroughly stirred sour cream and serve with rice.