(Note: This is the amount I make, to feed our family of 6 eaters, plus have a little leftover for the next day. Quantities can be easily halved or cut into thirds for smaller families.)
1-2 pounds chicken thighs, chopped roughly into 1-inch cubes
1 & 1/2 cup soy sauce
1 & 1/2 cup sugar
6 Tbsp mirin/white wine (if you don't have this, as I never do, I sub in a splash of lemon vinegar)
2 Tbsp grated ginger
1 garlic, chopped fine/minced
1 & 1/2 tsp cornstarch
roughly 1/2 a tsp of red pepper flakes, give or take, according to your taste
***(as a sidenote, you'll want to start up your rice first, before you even chop the chicken. By the time it's done cooking, your chicken will be ready too.)***
Chop up the chicken. Nearly cover the bottom of a frying pan with vegetable oil, then add in chicken, and brown over medium-high heat. You want the chicken to be cooked, but still tender. Once chicken is cooked, add all other ingredients, in the order they appear above, to the frying pan, combine, turn down the heat, and simmer. Let thicken slightly, and then serve over rice.
Easy & delicious!