Peel, wash and cut the potatoes into pieces. Cut the sausages in half. Heat the oil in a pan and fry the sausages for 5-6 minutes. Take them out and put them aside. Add potatoes to the frying fat and fry over medium heat for about 15 minutes, turning several times.
In the meantime mix sour cream with mustard, season with salt and pepper. Clean, wash and cut leek into rings. Cook peas in boiling salted water for 2-3 minutes. Drain, chill and let drain. Clean, wash and quarter the radishes. Add leek to the potatoes and fry for 8-10 minutes more. Season to taste with salt and pepper. Mix in peas. Cut cress from the bed and sprinkle over the pan with the radishes.
Clean, wash and quarter the radishes. Add leek to the potatoes and fry for 8-10 minutes more. Season to taste with salt and pepper. Mix in peas. Cut cress from the bed and sprinkle over the pan with the radishes. Spread the sour cream on the pan