Cook the spaghetti in salted water until al dente.
In the meantime, sweat the onion cubes in the frying fat in a large pan until translucent. Reduce the heat, spread the smoked salmon on the onions and cover the pan. The fish is done after about 5 minutes. Now cut up the salmon with a ladle, add the dill and mix everything together.
Put the drained spaghetti directly into the pan and mix with the salmon. Arrange on plates and grind pepper over them.