Prepare the marinade first. Stir together the soy sauce, brown sugar, water, garlic, ginger, and 1 Tbsp of the cooking oil in a bowl.
Place the chicken in a shallow bowl or dish, then pour the marinade over top. Turn the chicken a couple of times to make sure it's well coated. Let the chicken marinate for 30 minutes to one day (refrigerated), turning the chicken occasionally as it marinates.
When ready to cook the chicken, heat the remaining 1 Tbsp cooking oil in a large skillet over medium heat. Once hot, add the chicken, discarding the remaining used marinade.
Cook the chicken for about 5-7 minutes on each side or until cooked through and the liquid in the skillet has reduced to a light coating of glaze on the chicken.
Transfer the chicken to a cutting board and let it rest for about 5 minutes before slicing and serving.
*You can make this teriyaki chicken with boneless, skinless chicken thighs or breasts, or even chicken tenders. I find chicken thighs to be the best for this recipe because they cook quickly and stay super tender and juicy. If using chicken breasts, make sure to fillet them into two thinner pieces or pound the chicken to a ½-inch thickness before marinating. This will help them cook quickly and evenly in the skillet before the glaze burns.**Cooking Oil helps the sauce stick to the chicken and helps the chicken cook without burning whereas water helps thin the sauce to the correct consistency.***Soy sauce is the savory and umami base for the sauce. Garlic enhances the savory flavor of the sauce, ginger adds sweetness and spiciness. Brown sugar increases the richness and sweetness to the sauce.