Defrost the peas. Wash the potatoes and boil them in a little salted water for about 20 minutes. Dice ham and onion. Wash and quarter mushrooms. Boil the egg for about 8 minutes until soft
Sear the ham without fat in a coated pan. Stir-fry the onion and mushrooms for about 5 minutes. Season with pepper and possibly salt. Deglaze with 100 ml water, bring to the boil and stir in broth. thicken sauce and stir in sour cream
Drain the potatoes, except for some potato water, and mash them finely. Stir in milk and peas, season to taste. Heat briefly. Quench egg, peel and halve. Arrange everything and sprinkle with cress if necessary