Rinse and cook 2 cups of short grain white rice in an instant pot or on stovetop. (You can refer to my post on "how to cook rice using 3 different methods" for instructions.) Slice the spam into pieces that are 2 inches wide and 1/4 inch thick, then fry them in a pan until they are crispy on both sides. If you are using a 12 oz can of spam, you can cut it into 12 slices, but for this recipe, only 6 slices of spam are required.
Transfer the cooked rice to a large mixing bowl, add ¼ cup of soy sauce to the rice, use a rice spoon to stir the rice until the rice is evenly colored.
Line a small bowl with a sheet of plastic wrap, add ½ cup of rice to the bowl. Gently press the rice with a spoon.
Take a slice of cheese and fold it in half, then fold it in half again to create 4 small cheese squares. Place 2 of the cheese squares in the center of the rice, followed by a slice of spam on top of the cheese. Add the remaining 2 cheese squares on top of the spam to complete the filling.
Add ½ cup of rice to the bowl. Gently press the rice with a spoon to cover the filling.
Fold the plastic wrap over the rice, flip the bowl over to unmold the rice ball. Press the rice ball firmly with your hands to ensure it's compact and holds together.
Do not remove the plastic wrap, use your hands to shape the rice ball into a triangular shape.
Remove the plastic wrap. Place the onigiri on a plate lined with plastic wrap. Repeat these previous steps until all the onigiri have been filled and shaped.
Optionally dust and brush a thin layer of cornstarch of both sides of each onigiri to create a crispier exterior.
Mix 1 tbsp of soy sauce and ½ tbsp of honey in a small bowl. Set aside by the frying pan.
Place a non-stick frying pan on medium heat and add 1 tsp of butter or vegetable oil for each onigiri that will be pan-fried. You may need to fry the onigiri in multiple batches depending on the size of your frying pan.
Once the butter is melted, place the onigiri in the pan and cook until it turns crispy on both outsides.
Once the onigiri is crispy, brush the soy sauce honey mixture on both sides of the onigiri. Keep frying until the onigiri turns golden brown on both sides. (Please note that the onigiri will color quickly after being brushed with the soy sauce honey mixture, so it's important to turn it frequently to prevent over-coloring or burning.)
Once the yaki onigiri is golden brown, transfer it to a serving plate. You can wrap it with a thin strip of nori, or sprinkle a dash of nori komi furikake rice seasoning onto the center of the yaki onigiri. Serve hot.