An all-time classic Hawaiian dish. My old roommate in college, Brandon, introduced me to the glory of musubis when he would make them late at night when we were all super drunk. I have been addicted to them ever since.
Add a bit of oil to a skillet and preheat your stove to medium.
Cut the spam into 4 equally thick pieces. Salt each side.
Brown the spam in the pan for a few minutes, then set aside.
Clean out the oil from the skillet (or grab a new one) and cook the sugar, soy sauce, and mirin over medium-low heat to form a teriyaki glaze.
Add the spam to the pan with the glaze and cook another couple minutes until the spam is nicely glazed with teriyaki. Remove the spam and keep it on a plate while you prepare the next step.
Each square nori sheet should be able to be cut into two rectangles roughly the width of a piece of spam. You want to lay out a layer of rice about 1/4 inch thick that's roughly the same shape as your piece of spam on to the edge of each rectangle of nori. You can use a musubi mold for this or a spam can.
Lay the spam on top of the rice.
Roll up the nori until it's wrapped completely around the rice and spam, and use some water on your fingers to seal it up.
Serve with some la yu chili oil for an extra zing.