1. Combine garlic power, onion powder, paprika, salt, and pepper in a bowl. Rub them over the meat.
2. In a large pot, sear the meat on both sides until browned.
3. Make the sauce: Heat avocado or coconut oil. Sauté onion until translucent, then combine with remaining sauce ingredients.
4. Transfer the sauce and meat to a sous vide bag. Cook on 136.4 degrees Fahrenheit (58 degrees Celsius) for four hours (for a medium roast). Remove meat from the bag and reserve sauce. Allow the meat to rest for 10 minutes before slicing. Serve with the reserved sauce drizzled over the meat.
To prepare in the oven: Season roast and allow to marinate overnight in the fridge. Follow directions for sauce above. Pour the sauce over the roast and cover tightly. Bake at 350 degrees Fahrenheit for one hour. Uncover and bake an additional 20 minutes or until browned. Allow to cool completely before slicing.