Boil the unpeeled potatoes and carrots soft on the previous day in salted water. Let them cool down completely. To make the salad, peel the boiled potatoes and carrots and chop into fine cubes. Grate the boiled and cooled eggs. Chop the cucumber, apple and sausage into fine cubes, add the tinned peas. Mix the sour cream and mayonnaise together into a sauce, season with salt and pepper. Pour the sauce onto the salad and mix up gently. Let the salad season for a few hours.