Soak 1 cup short grain rice with 2 cups water. Soaking the rice in water helps soften the rice as short grain rice can be hard in the center if not soaked.
Slice ½ small white onion in thin slices.
Prepare the chicken marinade by mixing ½ tablespoon instant dashi powder, ¼ teaspoon salt, 1 tablespoon soy sauce, ½ tablespoon dark soy sauce, 1 tablespoon mirin, 1 teaspoon sugar, ½ small white onion, and ½ tablespoon oil. Mix well and set aside.
Wash your chicken thighs in running water until it runs clear. This ensures your chicken does not taste gamey.
Cut you chicken thigh in 1 inch pieces. Add the cut chicken in the marinade from Step 3.
Wash the soaked rice in a strainer (or in the same bowl you used before) until water runs clear. Make sure your strain all the water to ensure that you add the right amount of water in the next step. The water should barely cover the surface of the rice. We don’t need to add too much water because the chicken and onions will provide some moisture to the rice and we don’t want soggy rice.
In the pot with rice, add ½ cup water and marinated chicken and onions from step 5. Place pot in rice cooker and press the cook button. If you don’t have a rice cooker, use the alternative cooking instructions below.
Beat eggs to 70-80% mixed with some egg white showing. Leave in room temperature.
When the rice is done cooking, open the lid really fast and pour the beaten eggs in. Close the lid and wait for 2-8 minutes (3 minutes for runny eggs, 5 min for over easy and 8 min for well done); depending on your rice cooker, you might need to press the button again!
Garnish the rice with some sliced green onions. Oyakodon is served with the chicken and egg sauce on top of the rice, so no need to mix everything together. Hope you enjoy!