Mock tender steak is an inexpensive cut of beef for a reason. The steak is usually rife with fibrous muscle and connective tissues that is chewy to eat, and easily dried out. It is not an ideal steak for grilling because the dry heat often saps moisture from the meat and hardens its texture. But if grilling is your only option for mock tender steak, there are extra measures you can take to improve the tenderness of the meat and produce an edible mock tender off the grill.
Hammer the surface of the steak with a meat tenderizing mallet. This will break down the tough fibers, producing a more tender piece of meat. This will probably thin out the meat a little, but do not hammer to the point that the steak starts to lose its form.
Place the mock tender steak over night in an acid-based marinade. Acid-based marinades like fruit-based marinades and vinaigrette will break down the tough tissues that tend to produce tough grilled steaks. Set the steak in a plastic container and pour the marinade over the steak. Set the container in the refrigerator overnight.
Preheat your grill to high heat.
Place the steak on the grill's grates and cook for four to five minutes per side, turning once, for every 3/4-in. of thickness if you want a medium-rare steak. Increase the cook time by one or two minutes per side if you want your steak medium-well or well-done.
Remove the steak from the grill and serve.