In a large bowl, combine the salt, 1 teaspoon of the paprika, 1/2 teaspoon of the onion powder, and 1/2 teaspoon of the garlic powder. Add the buttermilk and whisk until the salt is completely dissolved and the spices are dispersed in the liquid. 

Cut the chicken lengthwise into about 1-inch-wide strips. Add to the marinade and let stand at room temperature for 30 minutes. (Do not marinate any longer or the chicken will be too salty. If you can't cook it right at the 30-minute mark, remove the chicken from the marinade and refrigerate until ready to continue.) 

In a large shallow dish (a 9 by 13-inch baking dish works well), combine the bread crumbs, the remaining 1 teaspoon paprika, the remaining 1/2 teaspoon of onion powder, and the remaining 1/2 teaspoon of the garlic powder. Add the 2 tablespoons oil and toss well to coat. Whisk together the egg whites and mustard in a second large shallow dish. Season both mixtures with pepper. 

Preheat the oven to 350 degrees F. Line a rimmed baking sheet with aluminum foil, then set an ovenproof rack on it. Coat the rack with nonstick cooking spray. 

Remove the chicken from the marinade, shaking off any excess, and thread onto sixteen 12-inch bamboo skewers, dividing the meat evenly, about 1 strip per skewer. Dip the chicken into the egg mixture, coating both sides. Place in the bread crumb mixture one skewer at a time, sprinkle with crumbs to cover, and press so the coating adheres to both sides. Gently shake off any excess crumbs and place the skewers on the prepared rack. 

Bake the chicken, turning halfway through, until golden brown and the juices run clear, about 25 minutes. Serve warm with the dipping sauce.

Vidalia-Honey Mustard Dipping Sauce:

Put the vinegar, onion, garlic, honey, and mustard in the bowl of a food processor fitted with the metal blade. Pulse until smooth. With the motor running, add the oil in a slow steady stream until thick and emulsified. Taste and adjust for seasoning with salt and pepper. Store in an airtight container for up to 3 days.