Mix chili powder, cumin, paprika, salt, oregano, salt, and red chili flakes together. Set aside.
Add the chopped onion and garlic to the slow cooker and mix with the tomato paste, lime juice, and 2 tsp of the spice mix.
Season the roast with the remaining spices, and place meat on top of the onion mixture. Cook on low for 7-8 hours.
After the meat has cooked, use 2 forks to shred and then mix well with the sauce in the slow cooker. Cover and cook on low an additional 30-60 minutes.
Serve with a warmed low-carb wrap/pita, cauliflower rice, or on a salad!
Nutrition: serves 10; calories 260; 2gm net carbs; 27gm protein.