Slice the cooked beef thinly and set it aside. Wash and prepare the fresh herbs, including cilantro, Thai basil, and perilla leaves. You can also include cooked shrimp or pork if desired.
Fill a shallow dish with warm water.
Dip each sheet of rice paper into the warm water for a few seconds until it becomes soft and pliable. Be careful not to soak it for too long, as it can become too soft and difficult to handle.
Lay the softened rice paper flat on a clean surface.
Place a few slices of beef and a selection of fresh herbs in the center of the rice paper, leaving some space at the edges.
Fold the sides of the rice paper over the filling, then roll it tightly away from you to enclose the ingredients completely. Make sure to tuck in the edges as you roll to prevent the filling from spilling out.
In a small bowl, mix together hoisin sauce, peanut butter, minced garlic, chopped chili (if desired), and lime juice to make the dipping sauce.
Cut the rolled Pho Cuon into bite-sized pieces and serve with the dipping sauce on the side.