Peel, wash and cut the potatoes into pieces. Cook in boiling salted water for about 20 minutes. Wash and clean the cucumber and cut in half crosswise. Slice both pieces lengthwise into thin slices. Mix mustard, honey and vinegar. Fold in 3 tablespoons of oil in a thin stream, season with salt and pepper.
Mix the salad dressing with the gherkins. Heat sesame oil in a frying pan and roast sesame seeds in it until golden brown. Wash the fish, dab dry, season with salt and pepper, turn in flour. Heat 2 tablespoons of oil in a frying pan. Fry the fish in two portions for 4-5 minutes, turning once. Keep warm. Heat milk and butter. Drain the potatoes and let them evaporate briefly. Mash with the hot milk mixture to a puree. Season to taste with wasabi and salt. Arrange mashed potatoes with fish, drizzle with sesame oil.
Keep warm. Heat milk and butter. Drain the potatoes and let them evaporate briefly. Mash with the hot milk mixture to a puree. Season to taste with wasabi and salt. Arrange mashed potatoes with fish, drizzle with sesame oil. Garnish with basil. Add wasabi, soy sauce and the remaining sesame oil