Bring a large pot of salted water to boil and cook the pasta according to packet instructions until just al dente. Drain and rinse under cold water until cooled.
While the pasta is cooking, make the dressing by mixing together the mayonnaise, greek yoghurt, chopped dill the juice of one lemon and a pinch of salt and white pepper.
Thinly slice the lettuce and wash well under cold water. Dice the red onion.
Season the prawns lightly with salt and pepper, then toss together with the lettuce, onion and pasta.
Serve with optional lemon wedges.
Notes
Serves 4 as a light lunch or side dish. Serves 2 as a main meal.