Cook the rice vermicelli noodles according to the package instructions. Drain and set aside.

In a large pot, heat the vegetable oil over medium-high heat. Add the garlic, onion, and ginger, and sauté for 2-3 minutes until fragrant.

Add the chicken broth, fish sauce, soy sauce, and sugar to the pot. Bring to a boil, then reduce the heat and let simmer for 10-15 minutes.

Season the broth with salt and pepper to taste.

To serve, divide the cooked rice vermicelli noodles into bowls. Add a few slices of roast duck on top of the noodles.

Ladle the hot broth over the noodles and duck.

Garnish with fresh herbs, lime wedges, and chopped chili pepper.