For the duck: Rub the breasts with half of the sesame oil and season with five spice powder and salt. In a hot saute pan add the remaining oil and sear the duck breast, skin side down, until skin had started to get crisp. Turn the breasts over and sear on the other side for one minute, then turn skin side down again and transfer pan to a 400 degree oven and cook until duck is medium. About 6 minutes. Remove breasts and set aside. When meat is cool enough to cut, slice very thin.
For the spring rolls: Lay a spring roll wrapper on a flat surface, then add a small amount of Asian greens, carrot and cucumber to the center of the wrapper. Lay three or four slices of duck on top of the vegetables. Fold each side of the wrapper in towards the center so the sides just touch. Then carefully roll the spring roll up tightly making sure the seal is tight. Repeat process until all rolls are completed.
For the vinegar: In a large bowl add all ingredients together and whisk.