Heat olive oil in a large skillet over medium heat. Add cabbage, onion, garlic, parsley, salt and pepper. Cook for 5-7 minutes, or until cabbage is soft and onions are fragrant.
Add mixture to a large crockpot, along with corned beef brisket (sprinkle seasoning over top of the meat), potatoes, carrots, celery, chicken broth and water. If the veggies are not completely covered by liquid, add water until they are.
Cook on Low heat for 7-8 hours. Remove corned beef from crockpot and place on a cutting board. Cut into small chunks, removing and discarding fat. Return meat chunks to the crockpot and cook for an additional 10 minutes.