Peel, wash and cut the potatoes into pieces. Boil potatoes in salted water for about 20 minutes. Peel, wash and chop carrots. Clean, wash and cut leek into rings. Add both to the potatoes after about 10 minutes and cook.
Boil the eggs for about 7 minutes until soft. Heat the fat in a saucepan. Sweat flour in it. Deglaze with milk and vegetable stock and bring to the boil while stirring. Season sauce with mustard, salt and pepper. Drain the vegetables and add to the sauce. Rinse, peel and halve the eggs. Arrange vegetables. Put eggs on top.
Season sauce with mustard, salt and pepper. Drain the vegetables and add to the sauce. Rinse, peel and halve the eggs. Arrange vegetables. Put eggs on top. Serve sprinkled with chopped parsley