Heat a wok over high heat until hot. Drizzle the oil down the sides to coat, and then add the garlic and chiles and stir-fry quickly. Add the mustard greens and stir-fry. Sprinkle the sugar over the greens and cook, stirring constantly, until the sugar has completely dissolved and has been absorbed by the vegetables. Set aside.
Split the rolls and stuff with the stir-fried pickled mustard greens. Top with cilantro and peanuts.