Cut potatoes into small cubes and microwave for 5 minutes at 500 watts or until soft.
Mash the potatoes until smooth.
Add in sushi vinegar, mayonnaise and wasabi and mix to combine.
Spread mashed potato mixture onto the nori sheet, leaving 1 centimeter from the top clean.
Arrange, cucumber, shrimp, egg omelette and kanpyo on top and roll up tightly.
Let it rest in the refrigerator for 10 minutes.
Slice and serve with sesame seeds if desired.