Wash and thoroughly dry the greens. If you're using choy sum, you can leave the stems whole or cut them into more manageable bites. If you're using a larger/tougher green like gai lan, slice the stems into relatively thin pieces to ensure that they cook evenly.

Combine the soy sauce, sugar and sesame oil and set aside.

Heat a wok over very high heat (as hot as you can manage) for about 30 seconds. Add the peanut oil and swirl to cover the bottom of the pan. Heat until the wisps of smoke begin to appear at the edges of the oil.

Add the ginger and garlic to the wok and stir-fry for about 30 seconds, or until the garlic is golden but not brown. Add the choy sum and stir-fry until the leaves are wilted and the stems softened; about 2 minutes. Try to make sure that the vegetables don't mound in the center of the wok, as this will prevent them from cooking evenly. Instead, you want to keep them as spread out as possible.

Add the soy sauce/sugar/sesame oil and stir/toss to ensure that the ingredients are thoroughly covered. Stir-fry for an additional 30-45 seconds or so to reduce the sauce and caramelize the sugars a little bit. Remove from heat and serve immediately.