Because collard leaves normally hide a lot of dirt, mud, or tiny insects, it is important to properly clean them to avoid ruining the dish. You basically need to soak the collards before cooking and here is how to go about it:- Make sure your kitchen sink is clean then fill it with cold or warm water (do not use hot water). Add a third of a cup of apple cider vinegar or your preferred choice of vinegar to the soaking water. You can also use 2-3 tablespoons of salt, instead of vinegar. Allow the collard greens to soak for 15 minutes (wash, rinse and soak at least three times, with each soak lasting for 5 minutes). Soaking the leaves helps the dirt settle at the bottom, making it easier to clean the leaves while the vinegar helps destroy any insects which may be present on the leaves.