Peel the potatoes and slice them into ½ inch-thick slices. Rinse these in cold water, then place in a pot of cold water. Add a pinch of salt and bring to a boil. Bring the heat down to medium-high heat and boil for 15-20 minutes until the potatoes are fully cooked.

Drain the water from the pot, and place the pot over low heat. Mash the potatoes with a potato masher for 1-2 minutes, then remove from the heat. Add the egg yolk and continue mashing until the potatoes are smooth.

Transfer the potatoes to a bowl and add the salt and mayonnaise and fully combine.

Place a large dollop of mashed potatoes onto a sheet of plastic wrap and wrap it around the potatoes. Gently shape the potatoes into the shape of a computer mouse, then unwrap the potatoes and place them on a serving plate.

Place some thinly sliced strips of nori seaweed onto the mouse to look like the buttons and like the cord. Press your fingers gently onto the buttons to create 2 indentations, and enjoy!