Peel and wash the potatoes and cook in boiling salted water for 15-20 minutes. In the meantime, boil the eggs for about 8 minutes until they are waxy, rinse with cold water, peel and quarter them. Wash and clean soup greens and cut into fine pieces. Cook in boiling salted water for about 5 minutes. For the sauce, heat up the fat and sweat the flour and mustard in it.
Deglaze with cream and vegetable stock. Bring to the boil while stirring constantly. Season to taste with salt, pepper and mustard. Carefully fold in potatoes, vegetables and eggs. Serve garnished with parsley