Cut chicken into bite-sized pieces.
Heat oil in wok over medium heat.
Add garlic and ginger to wok.
Cook aromatics for 30 seconds.
Add chicken pieces to wok.
Cook chicken until golden brown.
Pour coconut milk into wok.
Add soy sauce and oyster sauce.
Mix cornstarch with 2 tbsp water.
Add cornstarch mixture to wok.
Simmer sauce until it thickens.
Season with salt and pepper.
Garnish with chopped green onions.
Serve hot over steamed rice.