Put corned beef meat in a pot, add seasoning packet and extra pickling spice. Cover with water, bring to boil, then simmer for 2-3 hours with occasional water if needed, until beef is covered and cooked.
Once beef is tender (after at least 2 hours), add quartered onion, cabbage, potatoes, and carrots to the pot. Cook for 30 more minutes or until potatoes are tender.