Wash the cucumber and slice very finely. Wash the dill, dab dry and chop finely. Mix vinegar, salt, pepper, sugar and dill. Fold in 1 tablespoon of oil. Mix vinaigrette and cucumber and leave to stand. Wash the salad, pluck into bite-sized pieces and drain well in a sieve.
Heat 2 tablespoons of oil in a small frying pan, add fish bloxx and fry over medium heat, turning several times for 13-15 minutes. In the meantime, cut the buns about 3/4. Wash parsley, dab dry and chop finely. Fill cut rolls with lettuce leaves, cucumber salad, tartar sauce and one fish bloxx each. Serve sprinkled with parsley and fried onions