1. Trim the cauliflower florets, cutting away as much stem as possible. In 3 batches, break up the florets into a food processor and pulse until the mixture resembles chunky couscous.
2. Heat oil in large skillet and sauté onion until golden brown, about 4 minutes.
3. Add cauliflower and cumin and cook for another 4 minutes until soft.
4. Pour simmer sauce over veggies, stir and heat through.
5. Serve in warm tortillas with desired toppings.
If desired, serve with salsa, sour cream, tomatoes, cheese, cabbage, and/or avocado. Optional garnishes lime and cilantro.