Prepare all your ingredients by shredding the chicken, julienning the cucumber and bell pepper, and cooking the rice vermicelli noodles according to the package instructions. Drain and set aside.
In a small bowl, mix together the hoisin sauce, sesame oil, lime juice, and sriracha (if using) to create a dipping sauce. Set aside.
Fill a shallow dish with warm water. Dip one rice paper wrapper into the water for about 10-15 seconds, or until it becomes soft and pliable.
Lay the softened rice paper wrapper on a clean surface. In the center, layer a small amount of shredded chicken, carrots, cucumber, bell pepper, cilantro, and a few noodles.
Fold the sides of the rice paper wrapper over the filling, then roll it tightly from the bottom up to form a spring roll. Repeat with the remaining wrappers and filling.
Serve the summer rolls with the dipping sauce on the side.