How to Make It
In a very large skillet, heat 2 tablespoons of the oil. Sprinkle the brisket all over with 1 tablespoon plus 1 teaspoon of the spice blend. Add the brisket to the skillet and cook over moderately high heat until well-browned, about 5 minutes per side. Transfer the brisket to the slow cooker.
Add the remaining 1 tablespoon of oil to the skillet. Add the onion and garlic and cook over moderate heat, stirring occasionally, until softened, about 5 minutes. Add the remaining 1 tablespoon of the spice blend and cook, stirring, until fragrant, about 3 minutes. Add the stock and the tomatoes and their juices to the skillet and bring to a boil over high heat, scraping to release the browned bits on the bottom. Pour the mixture into the slow cooker. Cover and cook on high for 1 hour. Turn the heat to low and cook for 1 hour longer.
Add the black-eyed peas to the cooker, cover and cook on low for 3 1/2 hours, until the brisket and peas are tender.
Transfer the brisket to a carving board. Cover loosely with foil and rest for 15 minutes. Season the sauce with salt. Carve the brisket into 1/3 inch thick slices and using a large spatula, carefully return the brisket to the cooker. Turn off the cooker and let the brisket rest in the sauce for at least 15 minutes or up to 1 hour before serving.