Rinse the rice 2-3 times, then cook the short-grain rice according to package directions.

In a large measuring cup, add the eggs, mirin, salt, soy sauce, and sugar. If using cornstarch, mix it with water in a separate bowl first to dissolve all the cornstarch, then add this slurry to the cup with the eggs. Otherwise, just add the water to the eggs. Beat thoroughly until well-mixed.

Heat up a rectangular tamagoyaki pan or round nonstick skillet on low-medium heat. Once warm, brush a thin layer of oil.

Give the eggs a stir, then add enough to just cover the bottom of the pan in a thin layer. Let it cook until it sets.

Once the egg layer is about 80% cooked, use a spatula to carefully roll the egg onto itself towards the edge of the pan.

Brush the pan with more oil, then repeat with more of the egg mixture.

Once the new layer is about 80% cooked, use a spatula to carefully roll the egg and roll it towards the edge of the pan.

Slice the spam into 8 slices. Preheat a pan on medium heat, and brush lightly with oil. Add the spam slices in a single layer and sear both sides until golden brown.

Lower the heat to low-medium, and add all the glaze ingredients to the pan. Stir well. Once it’s thickened, add the spam back in and coat each slice with the glaze.

Fold the nori sheets in half, then in half again. Rip or cut the folded seams to create 4 strips per sheet.

Slice the tamagoyaki into 8 slices.

Using a musubi mold or a clean spam can, press down about ½ cup of cooked rice firmly. Season the top of the rice with a bit of the glaze from the spam, some furikake, a slice of spam coated in glaze, and a slice of tamagoyaki.

Face the nori strip shiny side up, then wrap it around the musubi, with the seam side facing down. Repeat until all the musubi are wrapped.