Yes, it is recommended to wash the liver before cooking. This is because the liver can carry harmful bacteria, which can be dangerous to consume. It's important to clean the liver thoroughly in order to reduce the risk of food poisoning. Start by rinsing the liver under cold running water and then soaking it in a mixture of cold water and white vinegar for at least 10 minutes. This will help remove any dirt or impurities that may be present on the surface of the liver. After this, you'll want to carefully scrub the liver with a soft brush or cloth to remove any excess fat or other contaminants that may still be present. Once you've carefully cleaned and washed the liver, pat it dry with paper towels before cooking and serving. Doing this step will also help prevent unpleasant odors from developing when you cook it.