1 cup soy sauce
1/2 cup granulated sugar
6 cloves garlic, crushed in a press
2 tablespoons grated fresh ginger
1 3-inch cinnamon stick
1 tablespoon pineapple juice (optional)
1 teaspoon molasses
2 tablespoons cornstarch

8 skinless, boneless chicken thighs

Combine everything but chicken and cornstarch in sauce pan and make sauce. Thicken slightly, pour over chicken and let sit for at least one hour. If baking, set oven to broil and cook three minutes per side, then bake at 425 until done. If grilling grill over high heat to sear then cook slower until done. brush reserved sauce over the top.

Can leave out pineapple and cinnamon with no major change in flavor. 

mostly from https://cooking.nytimes.com/recipes/1012984-chicken-teriyaki
but I added molasses instead of brown sugar and reduced sugar overall.