Fill a round dish (I like to use a 10-inch cake pan) with warm-to-hot water, about 160ºF.
Dip one of the spring roll wrappers in the warm water for a couple seconds, shake off the excess water, then lay flat on a cutting board.
Place a leaf of lettuce on the bottom third of the rice paper. On top of the lettuce, add a couple slices of cucumber, a few strips of jalapeño, about a 1/2 cup of soba noodles, a few leaves of Thai basil, and a generous sprinkle of green onions.
Begin to roll the rice paper wrapper from the bottom to the top, folding it over the ingredients. Tuck in the sides and continue to roll, just as you would a burrito. Set on a platter and repeat the process with the remaining ingredients.
For a pretty presentation, slice rolls diagonally before serving.