In shallow dish, combine chicken with melted butter, ginger, curry powder and salt. Turn several times to coat chicken.
Place chicken on grill preheated to medium heat. Cook 5 to 7 min. per side or until an instant read thermometer registers 165°F (74°C) when inserted into thickest part. Remove chicken from grill to rest.
Meanwhile, grill pineapple rings about 5 min., turning occasionally, and basting with 1 tbsp (15 mL) BBQ sauce, until softened and marked. Grill naan 2 to 3 min. per side until toasted.
Cut each naan in half; brush with remaining BBQ sauce. Thinly slice chicken. Sandwich chicken and pineapple between naan halves. Top with onion and cilantro leaves to serve (or tuck inside sandwiches, if desired).
To peel a pineapple and make into rings, use large sharp knife to cut off top and bottom to create flat surfaces. Placing knife on top surface just inside peel, run blade down sides of pineapple and follow natural curve of pineapple to slice off peel in sections. Lay peeled fruit on its side and cut into rounds. Remove woody cores with small round cookie-cutter.