Add onion, carrot, celery, bay leaves, cloves, apple juice, and water to the slow cooker.

Place the corned beef brisket on top of the vegetables.

Cover and cook on LOW for 8 hours until fork tender.

Transfer brisket to a cutting board and rest for 5–10 minutes before slicing against the grain.

Place thinly sliced cabbage into a large heatproof bowl.

In a saucepan, simmer red onion, caraway seeds, olive oil, and black pepper for 12–15 minutes until softened.

Remove from heat and stir in whole-grain mustard. Pour over cabbage and toss until slightly wilted.

Add salt, sherry vinegar, red bell pepper, and parsley. Toss again and adjust seasoning.

Arrange sliced corned beef over the warm cabbage salad and drizzle with a small amount of reserved cooking liquid before serving.