Adapted from Kirbie's Cravings and Rasa Malaysia
In a medium bowl, combine the chicken with all of the marinade ingredients and mix together well. Marinade at room temperature for 30 minutes.
Pour oil into a wok or cast iron skillet to the depth of at least one inch. Heat over medium-high heat until oil is about 350°F (you can also test the temperature by putting in a small cornstarch-coated chicken piece - it should sizzle vigorously). Put the cornstarch in a large bowl. Shake any excess marinade and seasonings off chicken pieces, and coat each chicken piece evenly with cornstarch. When the oil is hot, shake off excess cornstarch on chicken pieces, and place into oil.
Fry chicken on both sides until it turns golden brown, about 1-2 minutes per side. Fry a few pieces of chicken at a time, but don't crowd the pan too much, or the chicken won't turn out as crispy. When chicken is done, remove and place on a plate lined with paper towels to drain excess oil. Sprinkle chicken immediately with extra salt and white pepper while still hot, if desired, and toss to coat evenly (you can taste test one piece to gauge the flavor level).
After frying all the chicken, drop the basil leaves in the hot oil. The leaves cook quite fast, so you only need to fry them for a few seconds. Be careful as they will make a popping sound and may cause hot oil to sputter up. Sprinkle basil on top of chicken and serve immediately.