A Korean friend said to use a Kiwi fruit to tenderize them. But don't over do it or they will turn to mush. Trust me, I know this for a fact. Want to guess how I know this for a fact? Half of a kiwi is more than enough for about 5lbs of meat. A few hours should be more than enough.
I took a kiwi and rubbed both sides of the ribs and gave them a good coating of Simply Marvelous Peppered Cow and let them marinate for about 5 hours. Then onto a smoking hot grill for about five minutes per side. As my Texas buddy said, don't be afraid to put a little char on them, but be careful that you don't burn 'em.
Here's a link with some more info on them that I found.
How to buy and cook tablitas.
Turned out quite tasty!