Heat oil in wok over high heat.
Add garlic and chilies, stir quickly.
Add diced chicken to the hot wok.
Cook chicken until golden brown outside.
Add bell pepper, stir for two minutes.
Mix fish sauce, oyster sauce, and sugar.
Pour sauce mixture over the chicken.
Stir everything together for one minute.
Remove wok from heat immediately.
Add fresh Thai basil leaves on top.
Toss gently until basil wilts slightly.
Serve immediately over steamed jasmine rice.