In a wok or frying pan heat the cooking oil on medium high. Stir fry the garlic and chili until fragrant. Add the sliced chicken and stir fry until cooked through. It takes only a few minutes - don't overcook.
Now add the long beans to the wok/pan and stir fry a couple more minutes until slightly softened.
Stir in the chicken broth, oyster sauce, fish sauce, dark soy sauce and sugar until combined. Quickly stir in the basil leaves and take off heat.