1. Mix 1 cup water, paprika, rosemary, thyme, salt and garlic in slow cooker. Add onions. Place brisket in slow cooker and turn to coat with liquid. Cook on low for 6 to 8 hours.
2. Add sweet potatoes and continue to cook until brisket is fork-tender and potatoes are soft but not falling apart, 2 to 3 hours more. Remove meat and sweet potatoes from cooker. Place meat on a cutting board and tent with foil; let stand 10 minutes. Slice meat and skim fat from sauce. Serve with sauce on side.