Heat the oven to 350°F and arrange a rack in the middle.
Combine mustard and egg whites in a shallow bowl and season well with salt and freshly ground black pepper. Toss chicken in mustard mixture until well coated.
Combine dukkah and Parmigiano-Reggiano in a wide, shallow dish and mix thoroughly. Roll each tender in the dukkah mix until well coated.
Thread a chicken tender on each skewer. Place chicken skewers on wire cooling racks. Nest each wire rack in a baking sheet and place in the oven. Bake until the meat is firm and the dukkah crust is golden, about 25 to 30 minutes. Serve the skewers with the vinegar-honey sauce.