Peel the cucumber and shave into fine slices. Lightly sprinkle the cucumber slices with salt and drain in a sieve for 15 minutes.
Peel and finely chop the onion. Mix with half the oil, the vinegar, honey, salt and pepper.
Wash the dill, pat dry and chop the leaves. Mix the drained cucumber with the dressing and dill.
Cut the fish diagonally into 2cm wide strips. Season the fish strips with salt, pepper and turn in the flour to coat.
Mix the breadcrumbs and the sesame seeds on a plate.
On another plate, whisk the egg and season with salt.
Dip the fish strips in the egg and then turn them in the crumbs, pressing firmly to coat.
Heat the remaining oil in a pan. Fry the fish strips over a medium heat until golden brown all over.
Remove the fish from the pan, drain on kitchen paper and serve with the cucumber salad.