In a medium bowl, mix together ketchup, brown sugar, soy sauce, pineapple juice, 2 Tablespoons olive oil, rice vinegar, garlic, ginger and sesame oil. Add a pinch of salt and pepper. Reserve 1/2 cup of the marinade and set aside.
Place cubed chicken in a large Ziploc bag and pour marinade mixture over, seal and place in the fridge for at least an hour. In the meantime, soak your skewers in water for the hour.
While the chicken is marinating, cut your onion, pineapple, and green onion. Place in a large bowl and drizzle with olive oil, salt, and pepper.
For grilling: Heat grill to around 400 degrees. After chicken is marinated, thread chicken, green pepper, pineapple, and red onion on skewer and repeat until all chicken has been used.
Brush grill grates with olive oil then place skewers on the grill for 5 minutes then brush the remaining marinade over top the chicken/veggies. Flip and brush remaining marinade on another side of chicken/veggies.
Grill another 4-5 minutes, remove and serve with rice.
For oven: Preheat oven to 400 degrees. Place skewers on a sheet pan covered with aluminum foil and sprayed with non-stick spray. Place skewers in a line along with the sheet pan. Cook for 5 minutes, remove and brush marinade over top skewers then flip and brush another side of skewers with marinade mixture.
Place back in the oven for another 5 minutes or until chicken is done. Remove and enjoy with a side dish.