Heat vegetable oil in a large skillet over medium high heat.
Cut chicken into roughly 1" chunks.
Take each piece of chicken and coat in flour (shaking off excess), dip in egg and then coat in corn starch (pressing to coat).
Cook chicken in skillet, several pieces at a time until golden and crispy (about 2 minutes per side).
Drain on paper towels.
Remove top and seeds and cut red pepper into roughly 1" pieces.
Cut onion into roughly 1" pieces.
Drain pineapple chunks.
Heat olive oil in a skillet over medium high heat.
Cook pepper, onion and pineapple, stirring occasionally, until tender.
Add in chicken and chili sauce until well combined, about 1-2 minutes.
If sauce doesn't appear thick enough, make a slurry of 2 tablespoons of corn starch and 2 tablespoons of water and add to skillet and continue stirring.
Garnish with sliced green onions.