Preheat the oven to 400ºF and cut the cauliflower into small pieces so they will cook quickly and evenly. In a large bowl, toss the cauliflower in the olive oil.
In a small bowl, mix together the garlic powder, cumin, smoked paprika, and salt. Shake the mixture over the cauliflower and toss well. For extra-crispy cauliflower, you can sprinkle on the arrowroot or corn starch last, and toss again until you no longer see white powder. (This is optional-- the cauliflower is delicious either way.)
Arrange the seasoned cauliflower on a large baking sheet, spreading the pieces out as much as possible. (Don't crowd the pan, or the cauliflower will steam instead of getting crispy.) Bake at 400ºF for 20 to 25 minutes, until the cauliflower is golden.
While the cauliflower is cooking, in a large bowl combine the tahini, lime juice, garlic, salt, maple syrup, and 1 tablespoon of water. Mix well with a whisk, and add more water, just 1 tablespoon at a time, until the mixture looks creamy. (You shouldn't need more than 2 tablespoons of water total.)
Add in the shredded cabbage and cilantro, and stir well, until the veggies are evenly coated in the dressing. Set the bowl aside to let the slaw marinate, for at least 10 mintues before serving.
To prepare the corn tortillas, you can spray them with olive oil on both sides, and arrange them in a single layer on a large baking sheet. (You may have to do this in batches-- I can only fit 4 tortillas per pan.) Place the tortillas in the oven to warm up on the bottom shelf for about 5 minutes, while the cauliflower finishes roasting. The shells will crisp up as they cool, so be sure to fold them over quickly after removing them from the oven, before they firm up.
Serve each taco shell with a generous portion of the creamy slaw, topped with a few pieces of roasted cauliflower. You can add any other toppings you like, such as sliced avocado or green onions, but the flavor is delicious even without any extras. Store leftover cauliflower and slaw in separate airtight containers in the fridge for up to 3 days.
Nutrition information is for 1 of 8 tacos, using corn tortillas. This is just a rough estimate, not a guarantee!To keep this recipe gluten-free, be sure to use tortillas made from corn, cassava flour, coconut flour, brown rice flour, or almond flour. You can also use thinly sliced jicama as a vegetable-based taco shell. (Trader Joe's sometimes sells pre-sliced ones!)