Place the beef brisket in the crock-pot and add onion, apple juice, brown sugar, mustard and all the spices.
Cook on high 4 to 5 hours if you are planning on slicing it.
If you want it to shred easily or fall apart, cook on high for 6 to 7 hours or 10 to 12 hours on low. Remove from the crockpot and slice or shred for the Reuben sandwiches and the Corned Beef Hash.
My pictures show the corned beef both sliced and shredded.
My family likes me to cook the brisket until it shreds easily for both the Reubens and the Hash.