Cook the pasta following pack instructions. Meanwhile, heat the oil in a saucepan, add the shallot and cook until softened. Add the crème fraîche, lemon juice and season. Stir in the dill, then remove from the heat and set aside.
Blanch the asparagus in boiling water for 1-2 minutes, then drain and cut into pieces.
Drain the pasta (reserving a little water for later) and return to the pan. Add the salmon and prawns, then pour in the crème fraîche mixture and add the asparagus. Toss well, until the pasta is coated and all the ingredients are heated through (add a splash of the reserved water to loosen, if needed).
See more Salmon recipes