Pat the beef brisket chunks dry with paper towels so the seasoning sticks better. In a large bowl, toss the beef with the orange juice, cumin, smoked paprika, thyme, black pepper, and salt until every piece is coated.

Place the seasoned beef into the slow cooker, spreading it out in an even layer. Pour in the cranberry sauce and stir gently to distribute it around the meat.

Cover and cook on low for 8 hours. Do not lift the lid during the first 6 hours, as the heat will escape and extend the cooking time. You want that low and slow approach for brisket.

While the brisket is cooking, combine the apple cider vinegar, brown sugar, and orange zest in a small saucepan over medium heat.

Stir constantly until the sugar dissolves and the mixture comes to a gentle bubble. Cook for 5 minutes, stirring often, until it thickens enough to coat the back of a spoon. Remove from heat and let it cool slightly.

After 8 hours, use tongs to transfer the beef to a large bowl and cover it with foil to keep it warm. Pour the remaining liquid from the slow cooker into a fine-mesh strainer lined with cheesecloth or a paper towel, pressing gently to extract as much liquid as possible. Discard the solids.

Stir the glaze into the strained cooking liquid until it is fully combined. Taste the sauce and add a pinch more salt if needed.

Spoon the sauce over the beef and serve. Before serving, use a food thermometer to verify the internal doneness of the beef, as safe temperatures can vary by country.