Steps

1. Slice 1/4 onion into bite-sized pieces.
   🕒 01:13
2. Remove any blood clots, tough tendons, bones, cartilage, and pinfeathers from 120g chicken thigh. Make cuts with the knife blade angled outward and shave along the tendons. Feel the entire piece with your hands to ensure no bones or tough tendons remain. Turn it over, stretch the wrinkled skin, and pluck any remaining feathers. [This is the key!] Perform this task quickly to prevent the chicken from warming up and spoiling from the heat of your hands.
   🕒 01:26
3. Lightly pound the chicken thigh to tenderize it, then rub it with your hands to smooth out the pounded marks. Slice it diagonally. [This is the key!] Slicing diagonally increases the surface area, allowing the flavors to penetrate better.
   🕒 02:26
4. Rub 1 tbsp sugar, 1 tbsp sake, and a pinch of salt into the sliced chicken thigh and let it marinate for 15 minutes. [This is the key!] Sugar and salt improve moisture retention, while sake tenderizes the meat and reduces any gamey smell. This ensures even flavor penetration.
   🕒 03:03
5. Mix 4 tbsp water, 1 tbsp mirin, 1 tbsp dark soy sauce, and 1 tsp dashi granules to create the sauce. Add the sauce and the sliced onion to a oyakodon pan or a small, shallow frying pan. Cook over low heat until the onion is tender. Cover with a lid and steam. [This is the key!] Covering and steaming brings out the sweetness of the onion. Low, slow cooking enhances sweetness and removes pungency.
   🕒 03:43
6. Once the onion is about 70% cooked, add the marinated chicken thigh. Once it boils, reduce the heat to low, cover, and steam. After 1 minute, flip the chicken to allow it to absorb the flavor evenly. Flip every 20 seconds or so until cooked through. [This is the key!] Cooking slowly over low heat prevents the muscle fibers of the chicken from contracting, resulting in a juicy texture. High heat will make it dry and overcooked, and too salty.
   🕒 04:05
7. Break 2 eggs into a bowl. Lightly break the whites, break the yolk membrane, and allow it to slightly seep into the whites, as if mixing gently. [This is the key!] Not completely mixing the egg whites and yolks creates different textures and flavors, as well as an appetizing appearance.
   🕒 04:58
8. Divide the cooked rice into three portions and place it in the bowls. [This is the key!] This creates space between the rice grains, allowing them to stand fluffy.
   🕒 06:14
9. Arrange the chicken so the most appealing side is facing up. Pour about half of the beaten egg mixture, starting with the parts with more visible egg white, into the pan, sliding your chopsticks to spread it. Cover and cook for 30 seconds.
   🕒 06:24
10. Add the remaining egg mixture, cover, and cook until it reaches your desired doneness. [This is the key!] If you prefer it slightly undercooked, remove it from the heat when it's a bit loose. It will continue to cook from the residual heat and become firmer.
    🕒 06:51
11. Pour the flavorful broth over the rice in the bowls. Carefully slide the egg and chicken mixture onto the rice. Garnish with mitsuba to finish.
    🕒 07:12