Gather all the ingredients. Reheat the ingredients (for food safety).
Place a plastic wrap on a working surface and put a sheet of nori seaweed on top (shiny side facing down), with a corner pointing up. I’m using an onigirazu mold to create the perfect shape.
Evenly spread the steamed rice in a thin layer and form into a square/rectangular shape in the center of nori sheet. Sprinkle a little bit of kosher salt. Salt is added to prevent the food from spoiling as we eat onigiri, onigirazu, and bento at room temperature, and typically without refrigeration.
Place the teriyaki salmon and asparagus on top. When you add the fillings, consider how you will cut the onigirazu later. You want to arrange fillings so when the ingredients are revealed it looks delicious.
Place thin layer of steamed rice on top, maintaining a nice square/rectangular shape. If you have a onigirazu mold, moist the “lid” before you press down so rice does not get stuck to it. Place the lid on top and press gently.
Pull up the mold carefully while pressing down the lid. If you’re not using a mold, make sure to stack the ingredients nicely.
Bring left and right corners of nori sheet towards the center. Fold gently but tightly to wrap around the rice and filling at the center. Then bring bottom and top corners towards the center. Continue to fold gently but tightly around the layers. Make sure the rice is tucked in nicely. If your onigirazu is a square shape, you can mark the onigirazu with a rice kernel so you will remember which way you wanted to cut.
Wrap tightly with plastic wrap. Set aside for 5 minutes with nori’s seam side down.
Cut the onigirazu with a sharp knife. Run your knife in running water before cutting so that the cross-section will be clean.
If you plan to make this the previous night, wrap the onigirazu with a thick kitchen towel and keep it in the refrigerator overnight. The towel will prevent the rice from getting hard due to the cold temperature. Consume the onigirazu within 24 hours.