In the onigiri mold, sprinkle a pinch of salt, then fill about halfway with rice. Dip your fingers/spoon with some water to help prevent sticking & create a small divot in the center.
Cover with the mold's top & firmly press down. You should feel a bit of resistance, otherwise, add a bit more rice. Press the back of the onigiri mold to release the triangle shape onigiri.
Brush soy sauce on the grilled rice balls, flip, & cook until each side is golden brown & caramelized. Keep a close eye so it doesn't burn. Carefully remove & enjoy immediately!