Marinate the chicken cubes in the BBQ spice rub with a little olive oil for at least 30 minutes.
Soak 4 wooden skewers in water to prevent them from burning on the barbecue.
Skewer the marinated chicken, alternating with vegetables (pepper, red onion, and olives) between the chicken pieces.
Add olive oil to a disposable aluminum grill tray (or aluminum foil).
Grill the skewers at 450°F directly on the aluminum tray.
Cook the skewers for 15 to 20 minutes.
Using a silicone brush, generously brush the skewers with BBQ sauce. Flip the skewers and brush the other side. Repeat this step 2 to 3 times.
Continue cooking for another 5 minutes and check with a knife to ensure the meat is fully cooked.