Fill a large bowl with very hot water. Dip one sheet of rice paper into the water and quickly rotate to moisten the entire sheet. It will become pliable. Lay the wet rice paper on a flat work surface. Arrange one lettuce leaf over the bottom third of the rice paper, flattening the lettuce to crack the rib. Spread a generous teaspoon of mayonnaise over the lettuce and top with three mint leaves. Add a few slices of pork and 1/2 cup of rice vermicelli noodles.