Wash the potatoes and cook in boiling salted water for about 20 minutes. Drain asparagus and cut into pieces. Wash lobster tails and cook in boiling salted water with caraway seeds for about 15 minutes.
Drain the potatoes, rinse with cold water and remove the skin. Cut the potatoes into slices. Peel onion, chop finely and fry in hot fat. Dust with flour and sauté briefly. Add wine, milk and cream and simmer for about 5 minutes.
Wash the dill, except for a few flags for garnishing, chop and add to the sauce. Season to taste with salt, pepper and nutmeg. Add potatoes and asparagus to the sauce. Remove the Langunstenschwän from the skin and cut into slices.
Serve with asparagus ragout on plates. Garnish with lemon and dill.