To impart a surprisingly complementary flavor to your steaks while simultaneously tenderizing the meat, marinate it with pineapple. That's right -- pineapple. It may sound odd if you haven't tried it, but this tropical fruit is one of few marinade ingredients that genuinely tenderizes; contrary to popular belief, most marinades merely add flavor to the surface of the food. To successfully tenderize steak without ruining its taste and texture, marinate for an appropriate amount of time.
The same process that tenderizes steak can also break it down into mush if you marinate it too long in the pineapple, and it'll start distorting the meat's color and taste. For cuts thinner than 1 inch, stick to about 10 to 15 minutes of soak time; for moderately thick steaks of 1 to 1 1/2 inches, marinate for roughly 15 to 20 minutes; and for thicker steaks, marinate for about 30 minutes.
Use a non-reactive dish to prevent damaging it or imparting an off taste into the meat. Glass, ceramic, stainless steel and plastic dishes work, or marinate in a sealed plastic bag. In this instance, you can marinate at room temperature, since the steak is out for less than 2 hours, the maximum safe time to be un-refrigerated. The less chilled the meat is at cooking time, the faster it cooks. If you're marinating in pineapple juice, add soy sauce or salt to balance the sweetness and tartness, along with spices and herbs, like black pepper and rosemary.