In a large non-stick wok or skillet, toast the rice over medium heat until golden brown, about 3 minutes. Like nuts, the rice can go from brown to burnt very quickly, so keep an eye on it. Remove the toasted rice to a coffee or spice grinder and pulse until it becomes a fine powder. Set aside.

Heat the oil in the skillet. Cook the garlic over high heat until golden brown, 1 to 2 minutes. Add the pork and cook, breaking apart with a spatula, until no pink remains, 5 minutes. Stir in the sugar and chiles and continue to cook until the pork begins to brown, 3 more minutes. Stir in the lime juice, fish sauce, shallot, and green beans and stir fry one minute more, until the vegetables are heated through. Add the herbs off the heat and taste for seasoning. Transfer to a serving bowl and garnish with the toasted rice. Serve warm alongside the lettuce leaves.