Mix together the marinade ingredients then add the chicken. Cover and place in the fridge to marinate for 30 minutes.
In a bowl, mix together the cornstarch, Chinese 5 spice, salt and pepper. Toss the marinated chicken with the cornstarch mixture.
Add about 1 inch of vegetable oil to a skillet, and heat over medium-high heat until hot. To check if the oil is ready, you can stick the end of a wooden spoon into the oil, and if bubbles form around it then it's ready.
Working in batches, add the chicken to the hot oil one piece at a time so they don't stick together. Fry the chicken for about 6-8 minutes, turning once, until golden brown and cooked through.
Transfer the cooked chicken to a paper towel lined plate to absorb the extra grease. Once you've finished cooking all the chicken, discard all but about 1 tablespoon of the oil. Add the diced onion and peppers. Cook for 3-5 minutes until the onion and peppers soften.
Transfer the chicken to a serving plate and top with the onion and peppers then garnish with green onion.
Salt and Pepper Chicken is great served with white rice or as an appetizer!