Prep the veggies. Wash and dry everything well.
Julienne the carrots and cucumber, shred the cabbage, and slice the bell pepper, avocado, and green onions. Pick the herb leaves from stems. Keep each ingredient in its own small pile for easy assembly.
Cook the noodles (if using). Boil rice vermicelli for 3–4 minutes until tender, then drain and rinse with cold water.
Toss lightly to prevent clumping and set aside.
Make the peanut sauce. In a bowl, whisk together peanut butter, soy sauce, vinegar or lime juice, sweetener, garlic, ginger, and chili sauce. Add warm water a tablespoon at a time until smooth and dippable. Adjust salt, acid, and heat to your liking.
Set up your rolling station. Fill a wide, shallow dish or large skillet with warm water.
Place a clean cutting board or damp tea towel next to it. Arrange your veggies, herbs, noodles, and lettuce within reach.
Soften the rice paper. Dip one sheet into the warm water for about 8–10 seconds. It should soften but still feel slightly firm.
Lay it flat on the board; it will continue to soften as you fill.
Layer the fillings. Place a piece of lettuce in the lower third of the wrapper. Add a small bundle of noodles, then a few sticks of carrot, cucumber, cabbage, bell pepper, and avocado. Top with fresh herbs and a sprinkle of green onions. Don’t overfill—that’s the biggest cause of tearing.
Roll it up. Fold the bottom edge up over the filling.
Fold in the sides, then roll tightly away from you like a burrito. If the wrapper tears, you can patch with a second wrapper or just keep rolling—the stickiness often seals minor tears.
Repeat. Continue with the remaining wrappers and fillings. Place finished rolls seam-side down on a plate.
If they stick, line the plate with a lightly oiled surface or parchment.
Serve. Slice rolls in half with a sharp knife, sprinkle with sesame seeds or crushed peanuts, and serve with the peanut sauce and lime wedges.