To wash the Chinese Broccoli, trim 1-inch from the ends of stalk and discard. In large wok or pan (large enough to hold all stalks), heat just 1 tablespoon of the cooking oil over medium heat. When the oil is just starting to get hot (the garlic should sizzle upon contact) add the whole garlic cloves and let them fry until golden brown on all sides. Be careful not to burn the garlic, you just want to toast them – if the garlic starts turning dark brown, turn the heat to low. Toasting the garlic should take about 2 minutes. While the garlic is toasting, in a small bowl mix the stock and Chinese rice wine (optional) and set aside.
Turn the heat to high and add the ginger, fry for 30 seconds. Add the Chinese Broccoli stalks and use your spatula to scoop up the oil so that every stalk has been bathed with the ginger/garlic-infused oil for 30 seconds.
Pour the stock mixture into the wok and immediately cover the wok with a tight fitting lid. Turn the heat to medium and let the vegetable steam for 3-4 minutes, until stalks can be easily pierced with a paring knife or fork.
Remove the gai lan to a plate, leaving any remaining stock mixture in the wok. To the wok, add the oyster sauce and sesame oil and bubble and thicken on high for 1 minute. Pour the sauce mixture over the gai lan and serve