To prepare kebabs, combine first 7 ingredients; toss well. Thread 3 steak pieces, 2 peach wedges, 1 onion wedge, and 1 bell pepper piece alternately onto each of 16 (12-inch) skewers. Place kebabs on grill rack coated with cooking spray; grill 6 minutes or until tender, turning occasionally. Place kebabs on a platter; cover loosely with foil. Let stand 5 minutes.
To prepare sauce, combine chopped parsley and next 5 ingredients (chopped parsley through garlic), stirring with a whisk. Spoon over kebabs. Garnish with parsley sprigs, if desired.