Peel, wash and cut the potatoes into pieces. Cover and cook in salted water for about 20 minutes.
Peel and finely chop the onion. Clean, wash and slice the cucumber. Wash the dill and shake dry. Put something aside for garnishing, cut the rest finely. Mix yoghurt, half lemon juice, half onion and half dill.
Season with salt, pepper and 1 pinch of sugar. Mix dressing and cucumber and let it stand.
Wash the fish, dab dry and cut into pieces. Briefly puree the breadcrumbs, the rest of the onion and lemon juice with a hand blender. Stir in the rest of the dill. Season with salt and pepper. Form approx. 8 meatballs.
Heat the oil in a coated pan. Fry the meatballs in it at low to medium heat on each side for about 3 minutes.
Drain the potatoes. Add milk and mash everything finely. Season to taste with salt and wasabi. Arrange 2 salmon cakes and 2 wasabi puree each. Garnish with lemon and dill. Season cucumber salad and add.