Heat oil in a large skillet over MEDIUM-HIGH heat. Add the onions, garlic, and hibiscus. Sauté, stirring often until onions softened, about 5 minutes.
Add cumin, oregano, piloncillo, and tomato paste, stir and continue to sauté another 2 minutes. Add beef broth, stir, reduce heat and simmer for 5 minutes. Remove from heat, allow to cool for 10 minutes.
Pat Brisket dry with paper towels. Liberally season with salt and pepper. Place in a slow cooker fat cap side up. Carefully pour or ladle onion and hibiscus mixture over Brisket.
Cover and cook on LOW for 9-10 hours, or overnight. Brisket is done when it is fork tender and easily shreds when pulled.
Carefully remove Brisket from slow cooker, place on cutting board. Slice brisket in half then shred both pieces with two forks.
Return to the slow cooker, stir into sauce. The cooked onion-hibiscus is edible.
Serve in warm tortillas with diced tomato, onion, and salsa.
Nutrition information per serving: 470 Calories; 272 Calories from fat; 30.2 g Total Fat (12 g Saturated Fat; 13.4 g Monounsaturated Fat); 114.3 mg Cholesterol; 546 mg Sodium; 15.8 g Total Carbohydrate; 1 g Dietary Fiber; 32.2 g Protein; 6 mg Iron; 430 mg Potassium; 0.1 mg Thiamin; 0.3 mg Riboflavin; 10 mg Niacin (NE); 0.4 mg Vitamin B6; 3 mcg Vitamin B12; 7.1 mg Zinc; 28.2 mcg Selenium; 122.1 mg Choline.
This recipe is an excellent source of Protein, Niacin (NE), Vitamin B6, Vitamin B12, Iron, Selenium, Zinc and Choline. It is a good source of Riboflavin.