Trim any excess fat from the chicken thighs and season them with salt and pepper.
In a skillet with a lid, heat one tablespoon of oil over medium heat. Add the chicken thighs and cook for five to 10 minutes or until the chicken is nicely browned on one side. Flip the thighs over and saute for another five to 10 minutes, with the lid on, until the chicken reaches an internal temperature of 165 degrees.
While the chicken cooks, add the other tablespoon of oil to a saucepan over medium heat.
Add the ginger and saute for three to five minutes. Toss in the minced garlic and saute for a few more minutes until it is very lightly browned.
Add the rice vinegar, sake, soy sauce, half-cup water and sugar to the saucepan. Stir to combine, and raise the temperature to medium-high to bring the mixture to a boil.
In a small bowl, combine the cornstarch with three tablespoons water.
Once the mixture in the saucepan is boiling, stir in the cornstarch. When it is again boiling, remove the pan from the heat and stir in the sesame seeds.
Pour the sauce in the skillet with the chicken (lid off), and let it cook down a bit to thicken the sauce, making sure to baste the chicken in the sauce as it cooks. After a few minutes, serve the chicken, along with extra sauce. We had ours over fried rice.