Place lamb in a large snap lock bag. In a small bowl, Whisk together miso, half the rice wine vinegar, honey, soy sauce and half the sesame oil. Pour over lamb and marinate for 1 hour.
Meanwhile, place potatoes in a large saucepan of cold water and bring to the boil. Boil potatoes for 10-12 minutes or until tender. Drain, cool and thickly slice potatoes.
Place the cucumber, chilli, green onions and coriander in a medium bowl. Combine remaining rice wine vinegar with sugar and drizzle over vegetables. Toss to coat and set aside.
Heat a char-grill pan or barbecue over medium-heat and cook drained lamb for 4 to 5 minutes each side, brushing regularly with marinade, or until medium-rare. Set aside to rest for 5 minutes. Thickly slice.
Place cooled potatoes in a large bowl, add remaining sesame oil, mayonnaise, green onions and mint. Season and toss to coat.
Sprinkle lamb with sesame seeds and serve with potato salad and cucumber pickle.
Lamb fillets or lamb mini roasts would be delicious in the miso marinade.
You could thinly slice lamb and serve as part of a miso soup with noodles, sugar snap peas, and shallots.
Carrot and radish could be used instead of cucumber in the pickle.