1. Coat cold cooking grate of grill with cooking spray, and place on grill. Preheat grill to 350° to 400°(medium-high) heat.
2. Gently combine pork and reserved 2 Tbsp. mayonnaise mixture until blended, using hands. Shape into 4 (4-inch-wide, 1-inch-thick) patties.
3. Stir together butter and next 3 ingredients in a small bowl until well blended. Sprinkle each patty with about 2 Tbsp. pecan mixture (about 1 Tbsp. on each side), gently pressing to adhere.
4. Grill pecan-covered pork patties, covered with grill lid, over 350° to 400° (medium-high) heat 6 to 8 minutes on each side or until a meat thermometer inserted into centers registers 155°.
5. Grill buns, cut sides down, 1 to 2 minutes or until lightly toasted. Serve burgers on buns with lettuce and Dried Apricot-Chipotle Mayonnaise.