Cook the pasta according to the instructions on the packet until al dente, rinse in cold water and leave to cool.
Hard-boil the eggs, rinse, peel and quarter. Dice the onion, slice the cucumber and dice the knockwurst. Put the noodles in a large bowl with the chopped ingredients.
Mix the yoghurt well with salt, pepper, mustard, mayonnaise and cucumber pickling water and pour over the salad ingredients.
Stir and chill for 3 hours.