For the spring rolls: Bring a large pot of water to a boil. Add the vermicelli or rice noodles and cook according to the package directions, 2 to 3 minutes. Drain, rinse with cold water and set aside.
For the ginger-peanut sauce: Combine the peanut butter, lime juice, maple syrup, soy sauce, ginger and red pepper flakes in a medium bowl and whisk together. Slowly add in hot water, 1 tablespoon at a time, until the desired consistency is achieved. (It should be thick but pourable.)
To assemble the spring rolls: Pour very hot water into a shallow dish or skillet and immerse a sheet of rice paper to soften for about 10 to 15 seconds. Transfer the rice paper to a cutting board and gently spread out the edges, taking care not to tear them. On the bottom third of the wrapper, place a small handful of cooked noodles and a layer of bell pepper, cucumber, mango and a few leaves of basil and cilantro. Gently fold over once, then tuck in the edges and roll until the seam is sealed, like wrapping a burrito. (It's OK if the first one fails; it may take a few attempts to get used to rolling them up.)
Place seam-side down on a serving platter and cover with a damp towel to keep fresh. Repeat with the remaining wrappers and filling. Serve with ginger-peanut sauce.