Bring a medium pot of water to a boil. Turn off the heat and drop in the rice noodles. Let them sit for 10 minutes to soften. (Or follow the noodles' package instructions, if this varies.)
Using a shallow pan, submerge a spring roll wrapper in water for about 10 seconds until it softens, then lay it on a work surface (cutting board or clean dish towel) and start layering in the veggies. Start with the lettuce, then add the carrots, cucumber, cabbage, bell pepper, scallions, cilantro, mint leaves, and some of the noodles. Make sure to leave about an inch border to wrap the roll.
Fold in the wrapper's sides and roll it up like a burrito. Place on a tray and cover with a damp dishtowel.
Serve with a peanut sauce or another sauce of choice. Garnish with lime, if desired.