1. Heat an outdoor grill.
2. Combine cumin, cayenne, salt and pepper in a medium bowl. Toss with pork to coat, rubbing seasonings into the meat with your hands. Place 4 or more pork pieces on each skewer.
3. Brush grill with oil. Arrange skewers over direct heat on grill and arrange corn (in husks) over indirect heat. Put lid on grill. Cook pork, turning skewers often, until browned on all sides, 6 to 8 minutes total. Cook corn, turning it once or twice, for 10 to 15 minutes. Let cool before serving.
4. Spread pesto on corn, and serve with pork and watermelon wedges.Leftovers Note
5. Store 2 cups of the pork pieces in an airtight container in the refrigerator for dinner on Friday.