Prepare the Noodles: Bring a medium pot of water to a rolling boil. Add the rice noodles and cook just until tender but still firm (al dente), following the package guidelines closely. Drain the noodles and rinse them under cold water to stop cooking. Transfer them back to the pot, stir in the toasted sesame oil and sea salt to season gently, then set aside.
Soften the Rice Paper Wrappers: Fill a shallow dish or pie pan with about an inch of warm water. Submerge one rice paper sheet for approximately 15-20 seconds until it softens but remains slightly firm to the touch. Remove it carefully and lay it flat on a clean, damp kitchen towel to prevent sticking.
Assemble the Rolls: Arrange about one cup of the prepared vegetables and herbs near your workstation. Place a few torn butter lettuce leaves across the lower third of the rice paper, leaving about an inch of space around the edges. Layer a small handful of noodles over the lettuce, followed by shredded cabbage, carrot sticks, cucumber strips, and jalapeño slices. Sprinkle the green onions, cilantro, and mint evenly on top.
Roll Up the Spring Rolls: Fold the bottom edge of the rice paper up and over the filling tightly, then fold in the left and right sides towards the center. Continue rolling firmly but gently upwards until the spring roll is fully sealed. Repeat these steps with the remaining wrappers and filling.
Make the Peanut Sauce: In a small bowl, whisk together peanut butter, rice vinegar, tamari, honey (or maple syrup), toasted sesame oil, and minced garlic until smooth. Gradually add water one tablespoon at a time until the sauce reaches a creamy, dippable consistency. Adjust sweetness or saltiness to taste if desired.
Serve and Enjoy: Plate the spring rolls whole or slice them diagonally with a sharp knife to showcase their colorful insides. Serve alongside the peanut sauce for dipping.