While lemon, vinegar, white wine, or mustard are all great choices for tenderizing tough cuts of steak, yogurt is the super ingredient that can make your steaks even more tender.
A marinade has acids that tenderize the meat by breaking down their proteins. Yogurt has lactic acid that does this task, and it does it slower and more gently than other acids.
That subdued action makes yogurt an ideal marinade to use for a longer period, as other acids can turn meat mushy if left on too long. Plus, yogurt also has calcium and bacteria.
While calcium activates the enzymes that break down collagen, one of the proteins in meat, the bacteria in yogurt are live and active cultures, which also help break down proteins.
Yogurt also coats a steak's outside and caramelizes uniquely when cooked. So, instead of the hard crisp, you get a flaky crispness that absorbs smoke a high-heat sear provides.