If you have a piece of beef that is tough, like flank steak, don’t worry, you can grill it to tasty perfection. How? First, coat the meat with olive oil, then rub with 1/4 cup each of fresh coffee grounds and black pepper. Chill for 30 minutes then cook as usual. This will work because the tannic acid in the coffee breaks down the tough meat muscle fibers so your dinner will be tender and juicy.