Drain pineapples, set aside, and reserve pineapple juice. Whisk together pineapple juice, cornstarch, garlic powder, soy sauce, chili paste, and water. Set aside
Heat oil in a large skillet over medium-high heat. Add onions & pepper, and cook until softened, about 5-7 minutes.
Add snow peas & chicken and cook for 5 minutes.
Stir in reserved mixture with the reserved pineapples, and cook, stirring constantly, until mixture has thickened.