Wash the asparagus, cut off the woody ends. Peel the white asparagus, put them in boiling salted water with 1 pinch of sugar, bring to the boil and cook for about 8 minutes. Add green asparagus after about 3 minutes. Drain the asparagus and let it drain well
Wash the fish, dab dry and cut into 4 slices. Season with salt and pepper. Mix sauce powder and 150 ml cold water with a whisk. Bring to the boil briefly while stirring. Remove from the stove, fold butter in flakes and fold in well. Stir in cream. Stir in lemon zest and juice
Wash the basil, shake dry and pluck the leaves from the stalks. Place the asparagus in a greased baking dish and pour half the sauce over it. Place salmon slices on top. Arrange basil leaves on the slices, except for a few for garnishing. Place the smoked salmon on top and pour the rest of the sauce over it
Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 25 minutes. Remove from the oven and garnish with basil placed to one side. Serve with jacket potatoes sprinkled with parsley