The pink colour can be confusing, as usually meat changes colour once it is cooked. This isn't the case with corned beef. Corned beef is a tough cut of meat so it needs cooking for a long period of time. At least 3 hours for a whole piece, if cooking on a stove top or 8 hours in a slow cooker. This will ensure the beef is tender.This soup will take 2 hours to cook as the corned beef is chopped into chunks.