To make the sauce: In a medium bowl, combine the fish sauce, lime juice, rice wine vinegar, water, brown sugar, garlic and jalapeño. Stir until all the brown sugar is dissolved. Cover and refrigerate until ready to serve.
To make the meatballs: In a medium bowl, combine the pork, garlic, green onion, cilantro, lemongrass, jalapeño, fish sauce, sugar, salt and black pepper. Mix until thoroughly combined. Scoop and roll the meat into 1 ounce balls (about 2 tablespoons), and place them on a plate.
Heat a grill or grill pan to medium-high heat. Lightly brush the grates with oil. Grill, flipping occasionally, for 10 to 12 minutes until charred on all sides or until the internal temperature reaches 160 F. Transfer to a clean plate and tent with foil to keep warm.
Cook the vermicelli noodles according to package directions.
To assemble salads: Divide the romaine, cooked noodles, daikon radish, carrot and cucumber evenly between 4 serving bowls. Divide and top each bowl with the meatballs. Garnish with green onion, mint, cilantro and crushed peanuts if desired.
Serve warm with lime wedges and dressing on the side, add as desired.