Fry the fish fingers according to the instructions on the packet.
Drain the cucumber salad on kitchen paper and collect the stock. Mix the apple cubes with the cucumber stock and stir in the salad cream.
Halve the rolls, brush the cut surfaces with the cream and sprinkle with cress. Cover the lower halves of the bun with lettuce leaves. Carefully place the fish fingers on the salad and cover with cucumber and onions. Place the top halves of the bun on top.