Cut the spam into 2x2x7 cm rectangular prism. One can of 340g of spam should yield about 6 rectangular prisms.
In a flat-bottomed bowl or container, combine low-sodium soy sauce, sesame oil, and sugar with a whisk until the sugar is well dissolved. Lay the spam prisms flat in the container, making sure there is enough space for each spam prism’s bottom side to be covered with the marinade. Marinate each side of the spam prism for 5 minutes. Once all sides are well marinated, remove spam prisms from the marinade and set aside to dry off excess liquid.
Heat 1 tbsp of canola oil in a frying pan over medium heat and fry the spam prisms for 1 minute on each side, or until slightly browned. Remove from heat and let cool.
Cut nori seaweed sheets into 6 rectangles of 7x12 cm. We used 3 nori sheets to get 6 rectangles.
To make a spam musubi roll, lay one nori seaweed rectangle coarse side up flat on a cutting board. Spread about 2 tbsp of cooked white rice on the coarse side of the nori sheet. You should get a flat, thin, uniform layer of white rice that covers the whole coarse side of the nori. To make spreading the rice easier, you can use the back of a wetted metal spoon.
Lay a saran wrap on a flat surface and place the nori rectangle on the saran wrap rice side down. Place a cooked spam prism at one end of the nori rectangle, aligning the 7 cm edge of the spam prism with the 7 cm edge of the nori rectangle. Spread about 1 tsp of cooked white rice along opposite end of the nori rectangle. Gently roll the spam prism and the nori sheet towards the opposite end using the saran wrap to avoid the rice from sticking to the board and to your hands. You should have a sushi-looking roll with spam inside, covered with a layer of nori sheet, and white rice on the outside.
Cover each side of each spam musubi roll with all-purpose flour. Then, dip the roll into beaten egg, covering all sides of the roll. Cover the roll generously with panko breadcrumb and set aside.
Repeat steps to make the other spam musubi rolls.
Add enough oil into a frying pan to get about ½ inch of depth and heat over medium high heat. Fry each spam musubi roll for about 30 seconds to 1 minute each. Make sure to regularly turn the rolls around while frying to get an even goldening on each side. Remove from heat and set aside to drain off excess oil.
Enter a stick into each fried spam musubi rolls.
Garnish with Japanese mayonnaise, furikake, and green onions.