Peel the potatoes and microwave for 5 minutes at 500 W.
Meanwhile, thinly peel the cucumber lengthwise with a peeler, reserving a small portion to cut into thin half moons.
Make a ring using the long slices of cucumber. The cucumber flesh should adhere easily, but if it doesn't, moisten it with water.
Place the potatoes from Step 1 in a plastic bag and mash them. Drain the canned crab meat, then blend it into the mashed potatoes with the green peas and seasonings, massaging the bag until the contents are evenly combined.
Spoon a dollop into the cucumber rings. Top with the cucumber half moons and thinly sliced tomato rounds, then serve.
Story Behind this Recipe
Using leftover potato salad, I created a cucumber-wrapped sushi gunkan maki ("battleship" sushi) that I had at a conveyor belt sushi shop.
When slicing the cherry tomato, to get firm rounds, slice as though shaving the skin from a variety of angles. Add other ingredients to the potato salad to create your own version.