Grill the pork over Direct Medium heat until the meat is firm and no longer pink in the center, 5 to 7 minutes, turning once. Cut into thin strips. Grill the tortillas over Direct Medium heat until lightly marked and warm, about 30 seconds per side. Lay the tortillas on a work surface. Spoon the refried beans in the center of each tortilla, spreading them to within 1 inch of the edge. Evenly divide the pork and salsa over the beans. Spoon some sour cream on top. Fold the bottom edge of each tortilla up and over the filling. Fold in the opposite sides just until they meet in the center. Roll up from the bottom. Serve warm.