Mix mustard seeds, red pepper flakes, allspice and cloves together.
Remove Beef from wrapper and rinse. Corned Beef comes pre-brined in it's packaging. (Using a pre packed meat cut allows you to cut down on curing time).
Place corned beef in slow cooker insert. Make sure it is pressed into bottom of the pot.
Pour water over corned beef, then add salt and sugar.
Add spice mix, bay leaf and cinnamon stick to corned beef.
Place lid back on the slow cooker insert and leave in your refrigerator for at least 2 days, 3 maximum. Turn corned beef over once a day to insure even curing.
After the curing process is complete, place insert, including spices and brining liquid into slow cooker and cook on high setting for 6 hours.
Remove corned beef from slow cooker, discarding extra spices, bay leaf, brining liquid and cinnamon stick.
Slice corned beef and serve. This recipe is delicious served traditionally with cabbage and potatoes, or as a tasty leftover Reuben sandwich lunch.