Place the cut up chicken in a large bowl and season with salt and pepper. Add 1/4 cup cornstarch to the bowl and toss to coat evenly.
Heat the vegetable oil in a large wok or skillet over medium-high heat. Once the oil is hot, brown the chicken on all sides (you may have to do a few batches to not over crowd your skillet), remove from the skillet once browned to a paper towel lined plate and keep warm.
Meanwhile whisk together the remaining ingredients (2 tsp corn starch, 1/4 cup sugar, 1/4 cup soy sauce, 1/4 cup pineapple juice, 2 tbsp rice vinegar, 2 cloves of pressed garlic, 1/2 tsp cayenne pepper and 1/4 tsp dried ginger in a medium size bowl. Once the chicken is cooked add the sauce to the empty skillet. Stir and let the sauce cook for about 3 to 5 minutes or until it thickens.
Add the chicken back to the skillet and toss to coat. Serve hot over a bed of steamed rice and garnished with sliced green onions. Enjoy!