Cook the pasta in salted water according to the instructions on the packet until al dente. Meanwhile, cut the Leberkäse into small cubes, quarter the tomatoes, the spring onions into rings and the cucumber into slices. Mix the sour cream with the mustard and season with salt and pepper.
As soon as the noodles are ready, some oil is heated in a large pan. Fry the Leberkäse in it, then add the pasta and fry briefly. Stir in the sour cream and mustard mixture and bring to the boil as well. Finally, fold in the tomatoes, cucumber and spring onions. The food should be served warm.