Yes, you can freeze carnitas! If you are making it with the intention of freezing, or planning to freeze a portion of the recipe (such as half), you will want to only cook them up to the point of broiling. Place the carnitas, or the portion you're going to freeze, into an airtight container or bag with sauce and freeze for up to 4 months. When you're ready to make them, thaw in the fridge overnight, reheat the meat and broil as instructed. If you've already broiled it and want to freeze the leftovers, you can as well! It still freezes great, you just may not want to broil for the second time as the meat can dry out.