Gather all the ingredients.
Mix dashi powder, mirin, sesame oil, soy sauce, and white sesame seeds in a bowl.
Add the mixture to the warm rice. Mix everything evenly.
Divide into four equal sections.
Form the rice balls in a triangle shape. If you can't make the shape, you can make them in a circle but two sides should be flat.
Heat a pan on medium. When it gets warm, add the 4 onigiri to the pan.
Cook until the surface gets brown and looks crispy. Flip the Onigiri to the other side and cook the same. (It depends on how crispy you want them, but it's usually about 3-5 minutes each side.)
Let's serve! Yaki Onigiri is good by itself.