While the brisket roasts, prepare the cranberry glaze. In a saucepan, combine cranberries, cranberry juice, brown sugar, balsamic vinegar, orange zest, cinnamon, and a pinch of salt. Bring to a boil, then reduce to a simmer and cook for about 15–20 minutes until the cranberries burst and the sauce thickens. You can leave it chunky or blend it for a smoother finish.