Take a leaf of lettuce and tear it into large 5-inch pieces and place it along the bottom half of the wrapper (see image) Place some rice noodles on top of the lettuce followed by a couple thin slices of avocado. Place a few carrots and cucumbers beside the lettuce, 2 pieces of scallion (or more) and then your shrimp sliced in half across the middle, pink side down. If desired, add some mint, basil or cilantro.