For the spice blend: Combine the salt, brown sugar, paprika, garlic powder, mustard seeds, coriander, cumin, ginger, oregano, cayenne and cinnamon.
For the braised beef: Bring the brisket to room temperature. Sprinkle with black pepper, then rub some of the spice blend onto the meat. Reserve 2 tablespoons spice blend for another use, such as Black Bean and Beef Chilaquiles with Fried Eggs. Heat 3 tablespoons oil in a large skillet over medium-high to high heat. Add the brisket and cook until browned. Transfer to a plate. Add the remaining 1 tablespoon oil, the garlic, celery, carrots and onions and season with salt and pepper. Cook, stirring, for 5 minutes. Stir in the chipotle puree and tomato paste and cook for 1 minute. Stir in the beer and cook for 1 minute more. Add the stock and tomato puree and bring to a low boil. Add the brisket, cover and braise in the oven until very tender, 2 1/2 to 3 hours.
Meanwhile, bake 12 drop biscuits according to the package instructions.
Transfer the brisket to a cutting board. Puree the sauce with an immersion blender or in a food processor. Slice the brisket. Reserve 1 1/2 pounds brisket for another use if desired, such as Black Bean and Beef Chilaquiles with Fried Eggs. Return the brisket to the sauce, stirring gently to coat.
For the apple-cabbage slaw: Whisk together the oil, vinegar, sugar and lime juice in a large bowl. Add the apples, cabbage and onions, season with salt and pepper and toss to combine. Top with the cilantro.
Divide the beef and sauce among plates and serve with the biscuits and slaw.
The beef can be refrigerated in the pureed sauce for a make-ahead meal. Reheat over medium heat, stirring gently. The slaw can be refrigerated until ready to serve.