In a 5-6 qt crock pot, place brisket with seasoning packet, carrots, parsnips, pearl onions, parsley, bay leaves, peppercorns and 3 cups of water. Cover and cook on high 4-5 hours. Or low for 6-7..depending on how your crock pot cooks, will determine final cooking time. I have 3 crock pots, all cook @ different rates. :)
Add cabbage, cook on high 1 hour 20 minutes more. ( I fry my cabbage, then add it pretty much at the very end. Cooking maybe 30 mins or so. We prefer the taste of fried cabbage, and that is why I do it this way.
To serve, cut corned beef across grain into thin slices.