In a small saucepan over medium heat, add the soy sauce, brown sugar, honey, rice vinegar, sesame oil, ginger paste, minced garlic, and red pepper flakes.
In a small separate bowl, whisk together the cornstarch and water until smooth. Drizzle into the pot slowly while whisking constantly. Bring mixture to a boil, stirring constantly, and boil for about 1 minute. Reduce the heat to low and allow to thicken.
Slice the chicken breasts in half widthwise and pound to even thickness to get 4 even pieces of chicken. Set aside in a large ziplock bag and pour 1/3 of the teriyaki sauce over the chicken beasts in the bag. Marinate for at least 30 minutes up to 6 hours.
Make sure your grill grates are clean and greased. To grease, dredge a paper towel in vegetable oil and holding it with tongs rub it all over the grate. Preheat the grill to medium heat about 375-450 degrees F. Don't go hotter than 450 to avoid drying out the chicken. Grill the chicken until completely cooked through (about 4-6 minutes per side depending on heat of the grill) Chicken should be at 165 degrees F at its thickest part. Remove 2 tablespoons from the reserved teriyaki sauce and brush that over the chicken as it grills. Reserve the rest of the teriyaki sauce for enjoying over the dinner.
Drizzle some olive oil and salt (to taste) to both sides of the sliced red onions and sliced pineapple rings. Grill the onion and pineapple (again, on a well greased grate) for 1-3 minutes per side and then remove to a plate.