Toss the tuna cubes in the BBQ sauce.
Divide the tuna, peppers and onions between the skewers and thread them onto the skewers alternating with tuna cubes, red and yellow peppers, and onion.
Grill over hot coals until done, brush with some BBQ sauce and remove from the heat.
Serve with sweet potato wedges and coleslaw.
*Tip: You can use any firm flesh fish that takes your fancy.