Lay the steak on a cutting board and slice through the middle( making a pocket)|
Season inside the pocket with the all purpose seasoning.
Slice the Garlic, Onion and mushrooms (thin) and put inside.
Hold the steak together with wooden skewers or tooth picks.
Season both side of the steak and put on the grill, cook until done adding BBQ sauce to both sides.
Remove the skewers/tooth picks and serve.