Heat a wok over medium heat, add oil and allow getting hot. Add garlic and stir fry until fragrant about 30 seconds. Add bok choy and cook for 30 seconds. Season with soy sauce, sugar, salt and stir fry for about one minute.
Pour water in the wok, cover and simmer until leaves are dark green and stems are tender, but not over cooked. Remove drizzle with sesame oil and pepper.