Peel, wash and chop the carrots and potatoes. Boil potatoes in salted water for about 20 minutes. Cook the carrots for about 10 minutes.
Wash the arugula, shake dry. Put some leaves aside for garnishing, cut the rest finely. Boil eggs for about 8 minutes. Then rinse and peel.
In the meantime peel and finely dice the onion. Fry in 2 tablespoons of hot fat until transparent. Sprinkle with flour and sauté. Stir in ¼ l water and ¼ l milk. Bring to the boil, stir in stock and simmer for about 5 minutes. Stir in mustard.
Season with salt, pepper and 1 pinch of sugar. Keep warm.
Drain the potatoes and carrots. 200 ml milk and.
Heat 1 tablespoon of fat. Add to vegetables and mash. Season to taste with salt and nutmeg. Add rocket salad to the mustard sauce. Serve with the carrot-potato masher. Halve eggs and add to the sauce.
Sprinkle pepper over it. Garnish with the rest of the arugula. Drink tip: Rhubarb spritzer.