Heat a wok over high heat until hot. Add 2 teaspoons oil. Swirl to coat. Add half the chicken. Stir-fry for 2 to 3 minutes or until browned. Transfer to a bowl. Repeat with 2 teaspoons oil and remaining chicken strips

Add remaining 2 teaspoons oil to wok. Swirl to coat. Add garlic, ginger, onions and chilli. Stir-fry for 30 seconds. Add choy sum. Stir-fry for 1 minute or until bright green.

Return chicken to wok with oyster sauce. Stir-fry for 1 minute or until combined. Stir through cashews and basil. Serve with steamed rice.

Thai basil, also known as holy basil, has purple stalks with reddish-green leaves. It has a strong taste and is traditionally used in stir-fries and salads.