In a medium-sized bowl, combine diced beef with Worcestershire sauce, a pinch of pepper, and cornstarch. Mix thoroughly and set aside to marinate for at least 15 minutes.

Heat oil in a wok or large skillet over medium-low heat. Add thinly sliced garlic and fry until golden brown and crispy, about 3-4 minutes. Remove and set aside.

Increase heat to high and add marinated beef in a single layer. Sear undisturbed for one minute, then stir and cook for another 2-3 minutes.

Lower the heat slightly and return fried garlic to the pan. Add butter and oyster sauce, mixing gently until the beef is coated.

Transfer to a serving dish, garnishing with fresh parsley or chives if desired. Serve with steamed rice.