Prepare the rice vermicelli according to package directions and transfer to a colander to drain. Rinse well with cold running water. Drain thoroughly before using. (The noodles may be prepared up to this point 2 hours ahead of serving.)
In a small skillet heat the peanut oil over high heat and add the shallots. Cook, stirring frequently, until golden brown and crispy. Transfer to a paper lined plate to drain. Reduce the heat to low and remove all but 2 tablespoons of the oil from the pan. Add the chopped green onions to the skillet and cook, stirring constantly, until soft but do not allow to brown, about 1 minute. Transfer green onions to a small bowl and set aside to cool to room temperature.
Divide the drained vermicelli, lettuce, bean sprouts, and cucumber evenly among 6 deep soup bowls. Top with the meatballs, spearmint leaves, and cilantro. Garnish with the peanuts, crispy shallots, and sauteed green onions. Drizzle generously with Nuoc Cham Sauce and serve immediately, with chopsticks and more Nuoc Cham sauce on the side.
In a small bowl combine the pork, shallots, garlic, sugar, fish sauce and pepper. Stir to combine well, cover, and refrigerate for at least 1 hour and up to overnight. Transfer to the freezer for 30 minutes, or until the mixture is partially frozen.
Place the rice in a small skillet and heat over medium-high heat, stirring constantly, until rice is toasted, golden brown and fragrant. Transfer to a plate to cool. When cool, place rice in a coffee grinder and process to a fine powder. Measure 3 tablespoons of the powder and set aside. Save any remaining powder for another purpose or discard.
Transfer the partially frozen meat mixture to a food processor and process to a completely smooth but stiff paste. Add the pork fat to the processor and process until smooth or finely chopped. Add the roasted rice powder and pulse several times to combine the mixture. Do not over process or the mixture will become sticky.
Preheat a grill to medium-low.
Transfer the meat mixture to a small bowl. Lightly oil your hands. Divide meat mixture into heaping 1 1/2 tablespoonfuls and roll each into a smooth ball. Recoat your hands with oil as necessary. Thread the meatballs onto the bamboo skewers, fitting as many as you can on each skewer.
Coat the grill lightly with oil and grill the skewered meatballs, turning occasionally, until cooked through, 20 to 30 minutes. Serve warm or at room temperature.
Yield: about 25 meatballs
Combine the garlic, chile and sugar in a mortar and pound with a pestle to a fine paste. Add the lime juice, vinegar, fish sauce and water and stir to blend. Stir in the carrot and serve immediately or refrigerate, covered and in a non-reactive container, for up to 2 days.
Yield: about 1 1/4 cups