Cut the Chicken thighs skinless and boneless into small, even-sized pieces.
Roughly chop the Birdseye chilli and Garlic.
Heat the Vegetable oil in a wok or large pan over medium-high heat.
Add the Garlic and Birdseye chilli and stir-fry for 30 seconds until fragrant.
Add the Chicken and stir-fry for 4–5 minutes until cooked through.
Stir in the Light soy sauce, Oyster sauce, Dark soy sauce and Sugar, if using.
Add the Chicken stock if the mixture becomes too dry and cook for 1 minute.
Remove the pan from the heat and stir through the Fresh Basil until just wilted.