Mopping in grilling is a wonderful way to enhance the flavor of meats. It’s particularly beneficial to use with tougher cuts of meat that need long cooking over low heat.A mop sauce is a thin liquid, often based on tomato juice, vinegar, apple cider, beer or a combination of these ingredients, that’s “mopped” onto food numerous times during cooking. Moisten the meat with mop sauce every 20 minutes or so while its over the coals. Use a long-handled basting brush that will stand up to the heat of the grill and be sure to close the grill’s lid immediately after mopping.