Here is the recipe from the America's Test Kitchen cookbook. (best cookbook ever)
8 bone-in, skin-on chicken thighs trimmed (I actually used boneless, and it still works great.)
2 tsp. Vegetable oil
1/2 cup soy sauce
1/2 cup sugar
2 TBS mirin, sweet sherry, or dry white wine
2 tsp. grated ginger
1 garlic clove minced
1/2 tsp. cornstarch
1/8 tsp red pepper flakes
1. Pat the chicken dry with paper towels, then season with pepper. Heat the oil in a 12-inch nonstick skillet over medium-high heat until just smoking. Add chicken, skin-side down.
2. Weigh down chicken with a heavy pot. Cook until the skin is a deep mahogany brown and very crisp, 15 to 20 min. (the chicken should be moderately brown after 10 min. If it is very brown, reduce the heat; if it is still pale, increase the heat)
3. Remove the weight and flip the chicken over. Reduce the heat to medium and continue to cook, without the weight, until the second side is brown and the chicken is thoroughly cooked about 10 min.
4. Meanwhile, whisk the soy sauce, sugar, mirin, ginger, garlic, cornstarch, and pepper flakes together.
5. Transfer the chicken to a plate. Pour off all of the fat from the skillet. Whisk the soy mixture to recombine, then add to the skillet and return to medium heat. Return the chicken to skillet, skin-side up, and spoon sauce over the top. Continue to summer until the sauce is thick and glossy, about 2 min more.
6. Eat it up. yum. yum.
Here it is cooking