Pound the round steak with a meat mallet before marinating it. Pounding meat that's soaked in a liquid will make a mess. Also, marinating only imparts flavor to the surface and just below it. Marinade can penetrate all the way through a cutlet, or at least close to it. This makes for a more flavorful finished product.

To tenderize a round steak with a mallet, lay it on a cutting board and cover it with a large sheet of plastic wrap. With enough force to flatten the meat, pound it, starting at its center. Use a downward motion, but one that angles slightly away from you. Radiate outward from the middle.

Marinate a pounded round steak for one to four hours. The more acidic the marinade, the shorter the soak time should be. Marinate in the refrigerator in a ceramic or glass dish. Use equal parts acidic liquid and cooking oil, along with salt and seasonings. For a tenderizing marinade, use milk, buttermilk, yogurt, papaya, pineapple or kiwi. Don't mix cooking oil with dairy products -- fruit juice or puree works, as does laying slices on the meat.