In a bowl, combine chicken thighs with finely chopped lemongrass, fish sauce, brown sugar, lime juice, and minced garlic. Stir to coat the chicken in the marinade and let sit for 15 minutes.

While the chicken marinates, boil water and soak vermicelli noodles for 2 minutes until translucent. Drain, rinse in cold water, and set aside.

In a mixing bowl, combine peanut butter, hoisin sauce, vinegar, splash of milk, and grated garlic. Whisk until smooth, adjusting with more milk if necessary.

Heat a non-stick pan over medium-high heat with canola oil. Cook marinated chicken for about 3 minutes on each side until golden brown. Let cool and slice thinly.

Hydrate rice paper by dipping each sheet in warm water for 2-3 seconds until pliable. Lay on a clean cutting board.

Assemble rolls by placing cilantro, slices of chicken, vermicelli noodles, cabbage, and carrots on the bottom third of each rice paper. Fold sides and roll tightly.

Serve assembled rolls with dipping sauce on the side, either whole or halved for easy eating.