Mix all the ingredients for the Marinade in a big bowl, stir to combine well. Add the chicken, coat well, and marinate for 30 minutes.
Heat 2-3 inches (5cm-7cm) of the oil in a pan or stock pot for deep-frying. Coat the chicken with the cornstarch evenly. Shake off the excess. Deep-fry the chicken until they turn golden brown, remove from the oil with a strainer or slotted spoon, draining the excess oil by laying them on a wire rack or a dish lined with paper towels.
In a clean pan or skillet, add the basil leaves and stir a few times before adding the chicken back into the pan or skillet. Remove from heat, add the pepper salt powder and toss well with the chicken. Serve immediately.
Notes
Thai basil leaves are optional if you can't find them. You can find the bottled pepper salt powder at Asian grocery stores.