Heat the butter in a saucepan, sweat the flour in it, add 300 ml of water and the cream while stirring. Stir in the stock, bring to the boil and let everything simmer for about 5 minutes. Season to taste with salt, pepper, lemon juice, honey and mustard. Wash, pluck, finely chop the dill and stir into the sauce.
Wash salmon, pat dry and cut into 4 pieces, season with salt and pepper. Peel the cucumber, cut in half lengthways, core and cut into slices.
Put the cucumbers in a greased baking dish. Spread the salmon on top, pour the sauce over it and cover everything with the prawns. Cook in a preheated oven (fan oven: 150 degrees) for about 20 minutes.
Boiled potatoes or rice taste great as a side dish.