Prep. Preheat the oven to 425˚F and grease a baking dish with cooking spray. Set aside.
Prepare the chicken. Pound the chicken breasts to an even thickness, but do not pound them thin. Arrange the chicken breasts on the bottom of the baking dish. Add sliced onions over the chicken and set aside.
Make the teriyaki sauce. In a mixing bowl, combine honey, soy sauce, rice vinegar, garlic, and ginger; whisk until thoroughly combined. Pour the sauce mixture over the chicken; make sure that the chicken is nestled down in the sauce.
Cook the chicken. Bake for 30 minutes, or until the internal temperature of the chicken reaches 165˚F degrees.
Let it rest. Remove from oven and transfer the chicken and cooked onions to a serving platter. Set aside.
Thicken the sauce. Transfer the remaining teriyaki sauce from the baking dish to a frying pan or a saucepan set over medium-high heat. In a separate bowl, whisk together the cold water and cornstarch until the cornstarch is completely dissolved. Pour the cornstarch mixture into the teriyaki sauce and whisk to combine. Bring the mixture to a boil and let it boil for about 1 to 2 minutes or until thickened.
Finish and serve. Remove the sauce from the heat and spoon it over the chicken. Garnish with sesame seeds and chopped green onions. Serve over rice.
Notes
Chicken: I used chicken breasts, but you can also use boneless chicken thighs. No matter what you use, make sure that the chicken is cooked thoroughly by checking for a 165ºF internal temperature at the thickest part.
If the teriyaki sauce is too thick, add a couple of spoonfuls of water to reach the desired consistency.
For a one-pan approach, bake chicken in an oven-safe skillet and whisk the slurry into the sauce post-baking.
The chicken can be marinated in the sauce for up to 24 hours in advance.
Store leftovers in the fridge for 3-4 days in an airtight container, reheating in the microwave or stovetop with a sprinkle of water if needed. You can also freeze the chicken in an airtight container for up to 3 months, defrosting overnight in the fridge before reheating.