Place each chicken breast between two sheets of plastic wrap or parchment. Gently pound the breasts with a meat mallet or rolling pin to an even thickness of about ½ inch. This step helps the chicken grill evenly and maintain juiciness. After pounding, season both sides lightly with kosher salt.

In a bowl, combine soy sauce (or tamari), toasted sesame oil, honey, brown sugar, garlic powder, and ground ginger. Mix thoroughly until the sugar dissolves. Reserve about ¼ cup of this marinade separately for thickening and basting later. Place the chicken in a resealable bag or shallow dish, pour the remaining marinade over the chicken, and refrigerate. Marinate for a minimum of 30 minutes, or up to 12 hours for stronger flavor. Avoid exceeding 12 hours to maintain good texture.

Transfer the reserved marinade (not touching raw chicken) to a small saucepan over medium heat. While warming, whisk the cornstarch with cold water to create a slurry. Stir the slurry into the sauce and cook gently, stirring constantly, until it thickens to a glossy glaze (about 3-4 minutes). Remove from heat and keep warm for basting.

Preheat your grill to medium-high heat (around 400°F). Make sure the grill grates are clean. Fold a paper towel into a small square, dip it in cooking oil, and use tongs to rub the oiled towel across the grill grates. This reduces sticking and helps prevent flare-ups.

Remove chicken from the marinade, allowing excess to drip off, and discard the marinade with raw chicken. Place the chicken breasts on the grill and cook for 5 to 6 minutes per side. Using an instant-read thermometer, aim for an internal temperature of 160°F as you cook. In the last 2 minutes of grilling, brush the thickened teriyaki glaze onto the chicken, turning to caramelize the coating evenly. Avoid basting earlier to prevent sugar in the sauce from burning.

Brush pineapple slices and bok choy halves lightly with cooking oil and season with a pinch of salt. Grill these alongside the chicken for 3 to 4 minutes per side, or until lightly charred but not blackened. This adds a pleasant texture and flavor contrast to the meal.

Remove chicken and sides from the grill. Loosely tent the chicken with foil and let it rest for 5 to 7 minutes. This allows the internal temperature to rise to 165°F and keeps the meat juicy by letting the juices redistribute. Garnish the chicken with toasted sesame seeds and sliced green onions. Serve alongside the grilled pineapple and bok choy, accompanied by steamed rice or your preferred base.