1. Remove the tender (the small, easily separable strip) from underside of each chicken breast. Cut breasts into 1/2-in.-wide strips diagonally across the grain, and cut each tender in half lengthwise.
2. Bring mustards, oil, garlic, zest, orange and lemon juices, Worcestershire, and honey to a boil in a 2-qt. saucepan over medium-high heat. Reduce heat to medium-low and simmer, whisking constantly, 1 minute or until thickened slightly. Remove from heat and season with salt and pepper. Let cool 10 minutes.
3. Working in batches, place several chicken strips between 2 large pieces of waxed paper and gently pound with a meat mallet to flatten chicken into pieces about 1/8 in. thick. Put strips in a bowl.
4. Pour mustard mixture over chicken and gently stir with a rubber spatula to coat. Chill, covered, at least 2 hours and up to overnight.
5. Heat grill to high (about 500°) and wipe cooking grate with a thick pad of oiled paper towels. Thread chicken onto skewers so that they lie more or less flat. Grill chicken, covered if using gas, 2 minutes. Turn over and grill 2 minutes more, or until cooked through (cut to test).
6. Serve skewers on a platter, sprinkled with parsley. Add orange wedges for squeezing.
Note: Nutritional analysis is per serving.
Total time includes 2 hours to marinate.