Toss cauliflower florets with olive oil, chili powder, cumin, garlic powder, salt, and pepper.
Spread cauliflower on a baking sheet and roast for 20-25 minutes, until tender and slightly crispy.
Warm tortillas in a skillet or microwave.
Assemble tacos by placing roasted cauliflower on tortillas, then topping with shredded cabbage, cilantro, lime juice, avocado slices, and crumbled feta cheese.