Peel and finely dice the onions. Wash, quarter, seed and dice the tomatoes. Dice cucumbers and corned beef as well. Heat 1 tablespoon of oil in a frying pan, fry onions until translucent, add cucumber, 3/4 of the tomatoes and corned beef and heat briefly.
Season with salt and pepper and keep warm. Put milk and 150 ml water in a small pot and bring to the boil. Remove from the heat and stir in mashed potato powder with a whisk.
Season with salt and nutmeg. Stir in the fat. Fold the corned beef and cucumber pan into the mashed potatoes and keep warm. Heat the remaining oil in a pan, add the eggs and fry over medium heat until golden brown.
Season with salt and pepper. Wash the dill, dab dry and cut finely. Arrange potato onion meat and 1 fried egg each on plates. Sprinkle with dill and remaining tomatoes and serve as you like, garnished with lettuce, tomato, dill flags and parsley.