Trim off the excess fat from the chicken thighs first.
Prep the lemongrass. If using fresh lemongrass, then chop it by hand then add it to food processor with the garlic cloves. (Or finely mince by hand)
Add oyster sauce, black pepper, garlic, brown sugar, Knorr seasoning, garlic and lemongrass. Marinate this for at least 4 hours or overnight for more flavor.
Air fry for approximately 13-15 minutes on each side at 375 degrees. The time will vary depending on your appliance. Cook until the internal temp reaches 165 degrees F. Let it rest for 5 minutes.
For the scallion oil, add the scallions, salt and oil to a heat safe bowl and microwave for 1 minute.