Rinse corned beef under running water and pat dry. Rub with spice mixture (recipe listed above) and place in dutch oven or deep oven-proof pot, fat-side up. Add water (enough to cover the beef and then some). Heat over medium-high heat on stove until boiling. Once the pot has reached a boil, skim off any scum that collects on top and then transfer, covered, to the oven.
Braise for 3 ½ to 4 hours, until very tender.
In a small bowl, mix together the coconut sugar and mustard until smooth. Set aside.
Remove the corned beef from the water and place on a baking sheet lined with aluminum foil or parchment paper. Allow to cool slightly. Carefully remove the fat from the top of the beef using a sharp knife and slicing horizontally. Discard the fat. Generously coat the top and sides of the corned beef with the coconut sugar-mustard mixture.
Increase oven temperature to 375 degrees.
Remove the cinnamon stick and bay leaves from the water in the dutch oven. Add the vegetables (cabbage, carrots, onion and potatoes) to the dutch oven, adding additional water to raise water level to about ½ full if necessary. Cover and place over medium-high heat on the stove. Cook until vegetables are tender, about 15-25 minutes.
Place the glazed corned beef back in the oven and bake for approximately 10-15 minutes, until glaze is bubbly and crackling. Remove from oven and allow to cool for 5-10 minutes on a cutting board.
Once vegetables are tender, remove from heat and drain the water.
Slice corned beef across the grain (see photo above) into ⅛-inch to ¼-inch inch slices. Plate a few slices of corned beef, a cabbage wedge, some carrots, potatoes and onion for each serving.