Preheat the grill to medium or 350 degF. In two thin (or 1 heavy) sheets of aluminum foil, place 1 chicken breast each and season with salt and pepper. Place 2-3 pineapple slices on top of each chicken breast. Divide and top pineapple slices with onion and sweet pepper.

In a bowl, combine the barbecue sauce, soy sauce, and garlic.

Pour the sauce evenly over both foil packets, but reserve 1/4 cup and set aside.

Seal the contents of the foil packets and place on the grill. Grill the packets for 10-15 minutes or until the chicken is cooked through. Flip the packets halfway through grilling.

When cooking time is up, open the packets and drizzle in the rest of the sauce remaining.