i've had cuban steak sandwiches and they were awesome! they are marinated in a salty garlic solution, what might be called a brine, with other spices and herbs like bay leaves, culantro, oregano, allspice, cloves, pepper and sugar.
as far as tenderizing goes, there's two ways: chemical or mechanical.
chemical is done by adding a tenderizing agent such as pineaple, papaya, or dairy/yoghurt which contain enzymes that help break down the meat tissue.
mechanical is to physically pound or stab the meat to break it down a bit. in the case of meat cubes, i'd get something called a jaccard to poke the whole steak before it is sliced. or you can just go to town on it with a fork on both sides until you can actually see it getting softer and beaten up.
i also can see how cubed meat would be great in a taco rather than ground, just like the way it workes better in many chili recipes. i'm gonna have to try that. thanks.
in nomine patri, et fili, et spiritus sancti.
Meh nom eh noh...doot dooooo do do do.