Combine the sauce ingredients (*) in a pan and add onion and bring to a simmer over medium heat for 1-2 mins.
Put in chicken and simmer until the chicken is just cooked through (for 2 ~ 3 mins).
Pour in the 2/3 beaten egg and cook with a lid over medium heat for 1 and a half mins. Pour in the rest of the beaten egg and cook with a lid over high heat for 10 seconds and turn off the heat. (adjust the hardness of the egg with the remaining heat)
Arrange the rice in a bowl and place the "chicken and egg mixture" over top. Garnish with chopped scallions and crushed red pepper (or shichimi spice powder).