1 tablespoon sweet paprika
2 teaspoons onion powder
Salt and pepper
1 teaspoon garlic powder
⅛ teaspoon cayenne pepper
1 5-pound flat-cut beef brisket, trimmed
1 tablespoon vegetable oil
3 onions, halved and sliced ½-inch thick
1 tablespoon brown sugar
1 tablespoon tomato paste
3 garlic cloves, minced
3 tablespoons all-purpose flour
1 cup low-sodium chicken broth
2 tablespoons plus 1 teaspoon red wine vinegar
3 fresh thyme sprigs
3 bay leaves
1. Combine paprika, onion powder, 1 teaspoon salt, garlic powder, and cayenne in bowl. Using fork, prick brisket all over. Rub spice mixture over brisket, wrap tightly in plastic wrap, and refrigerate for 8 to 24 hours. Unwrap brisket and place in slow cooker.
2. Heat oil in 12-inch skillet over medium-high heat until shimmering. Add onions, sugar, tomato paste, and garlic and cook until onions are softened and lightly browned, 8 to 10 minutes. Stir in flour and cook for 1 minute. Slowly whisk in broth, scraping up any browned bits and smoothing out any lumps; transfer to slow cooker.
3. Stir 2 tablespoons vinegar, thyme sprigs, and bay leaves into slow cooker. Cover and cook until beef is tender, 9 to 11 hours on low or 5 to 7 hours on high.
4. Transfer brisket to cutting board, tent loosely with aluminum foil, and let rest for 20 minutes. Let braising liquid settle for 5 minutes, then remove fat from surface using large spoon. Discard thyme and bay leaves. Stir in remaining teaspoon vinegar and season with salt and pepper to taste.
5. Slice brisket ½-inch thick against grain and arrange on serving platter. Spoon 1 cup sauce over meat and serve with remaining sauce.