Wash and cook the sushi rice according to packaging. Once done, put the vinegar and mix well.
Meanwhile, combine the soy sauce, vinegar, and sugar. Cut the nori into lengthwise. Set aside.
In a pan over medium heat, add the cooking oil. Pan-fry the spam slices until lightly brown on each side. Dip each slice in the prepared teriyaki sauce.
To assemble the musubi, shape the rice in a Tupperware or spam can to create an oval shape. Alternatively, you can simply shape it by hand. Place the cooked spam on top of the rice and wrap them around with nori sheets.