3 tablespoons packed brown sugar
1 tablespoon plus 1 1/2 teaspoons chipotle chili powder
2 teaspoons ground cumin
1 teaspoon celery salt
1 teaspoon garlic powder
1 teaspoon salt
1/2 teaspoon pepper
4 to 5 lb fresh beef brisket (not corned beef)
1 1/2 cups ketchup
1/4 cup apple cider vinegar
1/4 cup finely chopped yellow onion
1 tablespoon Worcestershire sauce
3/4 cup low-sodium beef, chicken or vegetable broth or water
Mix in small bowl brown sugar, chipotle chili powder, celery salt, cumin, garlic powder, salt and pepper.
Spray with cooking spray inside of 6-quart slow cooker. Place brisket in slow cooker and rub mixture all over brisket.
In another small bowl, mix 3/4 cup of the ketchup, onion, the apple cider vinegar, and Worcestershire sauce. Pour over brisket along with broth.
Cover and cook on Low heat setting six to eight hours until meat thermometer inserted in center of brisket reads 160°F.
Transfer brisket to cutting board; let stand for 10 minutes. Meantime, add remaining 3/4 cup ketchup to sauce in slow cooker; stir to combine.
Slice brisket thinly; place in serving plate. Spoon sauce over top.