To a medium saucepan, add all ingredients for the sauce except cold water and cornstarch. Whisk to combine, and bring to a boil over medium-high heat.

To a small bowl, add the 2 tablespoons cold water and 1 tablespoon cornstarch, and stir to combine.

Add the water and cornstarch mixture to the saucepan, reduce heat to low, and allow sauce to simmer for about 5 minutes while you make the chicken; whisk intermittently.

To a large ziptop bag, add the chicken, 3 tablespoons cornstarch, salt and pepper to taste. Seal the bag and shake to coat chicken evenly.

To a large skillet, add 3 to 4 tablespoons olive oil. Add the coated chicken and cook over medium-high heat for about 5 to 7 minutes, or until chicken has cooked through. Stir and flip intermittently to ensure even cooking. If the skillet seems dry while cooking, add an additional tablespoon or two of oil as necessary.

After chicken has cooked through, reduce heat to low, add the prepared sweet and sour sauce, stir to coat evenly, and allow it to simmer for a minute or two.

Optionally garnish with sliced green onions and sesame seeds, and serve immediately.