Marinate pork: Combine all ingredients listed under Lemongrass Pork. Marinate in the refrigerator for at least 30 minutes and up to a day.
Make Nuoc Cham: Whisk all ingredients for Nuoc Cham.
Bake spring rolls: Preheat oven and prepare spring rolls according to package directions.
Cook rice noodles: Cook rice noodles according to package direction (most need to soak in very hot water until tender).
Heat a wok or skillet over medium-high heat. When oil is shimmering, use a slotted spoon transfer pork to heated oil (be careful - it will splatter when it hits the hot oil). Cook pork on one side until deep golden brown, 3 to 4 minutes. Stir pork and continue cooking until it is just cooked through, 1 to 2 minutes more.
Chop baked spring rolls into bite-sized pieces. Use kitchen shears to chop up rice vermicelli into shorter lengths.
Assemble bowls with a bed of lettuce topped with rice vermicelli. Arrange carrots, cucumbers, pork, spring rolls, peanuts, and fresh herbs on top. Serve Nuoc Cham on the side.
