Step 1

Combine oyster sauce and 1 tablespoon cold water in a bowl. Heat oil in a wok over medium heat. Add garlic and onion. Stir-fry for 1 minute or until onion has softened.

Step 2

Increase heat to medium-high. Add mince. Stir-fry for 3 to 4 minutes or until browned.

Step 3

Add chestnuts, beans and oyster sauce mixture. Stir-fry for 2 minutes or until beans are tender. Spoon into lettuce leaves. Serve with rice.