Drizzle the oil in a large wok or pan and place over medium-high heat.
Once thoroughly heated, add the chicken pieces and sprinkle with salt and pepper. Cook, stirring often, until browned and cooked through.
Remove the chicken to a plate and reduce heat to medium.
In a small bowl, whisk together the cornstarch and water until smooth.
Pour the teriyaki sauce into the pan and bring to a boil.
Reduce heat to a simmer and pour in the cornstarch mixture.
Allow to cook, whisking often, until the teriyaki sauce has thickened. Toss in the chicken and diced pineapple and cook until well-coated and hot. Remove from heat.
Serve the Pineapple Teriyaki Chicken with cooked white rice in the prepared pineapple boats or bowls and top with sliced green onions and sesame seeds.