This recipe is a modern twist on the Chinese classic - Peking duck with moo shu pancakes. Crisp, refreshing cucumber and full-bodied dressed crab are delicious with hoisin sauce in warm tortilla shells. You can find hoisin sauce in the aisle of your grocery store where Asian ingredients and other ethnic food are sold. This makes a great al fresco lunch for two but if you want to serve these as appetizers, double or triple the recipe; everything in this recipe multiplies easily.