In a small skillet, toast the rice over high heat, shaking the skillet a few times, until the rice is golden brown, about 3 minutes. Transfer the rice to a spice grinder and let cool completely. Grind the rice to a powder.
In a large skillet, heat the oil. Add the turkey and cook over moderately high heat, breaking up the meat evenly, until no pink remains, about 4 minutes. Add the stock and cook, stirring, until bubbling. Remove from the heat and stir in the fish sauce. Season with salt and black pepper and stir in the lime juice. Let stand for 5 minutes, then stir in the lemongrass, scallions, shallot rings, cilantro, mint, crushed red pepper and rice powder.
Arrange the lettuce and lime wedges on a platter. Spoon the laap on top and serve.