Prep the oven and pan: Heat the oven to 450°F (230°C). Line a large baking sheet with parchment paper for easy cleanup and better browning.
Season the cauliflower: In a large bowl, toss the florets with olive oil.
In a separate small bowl, mix cornstarch, chili powder, smoked paprika, cumin, garlic powder, onion powder, salt, and pepper. Sprinkle the mix over the cauliflower and toss until evenly coated.
Roast until crisp: Spread the cauliflower in a single layer on the baking sheet, leaving space between pieces. Roast for 20–25 minutes, flipping once halfway, until edges are deeply golden and crisp.
Make the sauce: While the cauliflower roasts, whisk mayo, yogurt, lime juice, adobo sauce, honey, and a pinch of salt.
Adjust lime and heat to taste. The sauce should be creamy, tangy, and slightly smoky.
Toss the slaw: Combine cabbage, cilantro, lime juice, olive oil, and salt. Toss and let it sit so the flavors meld while the cauliflower finishes.
Warm the tortillas: Heat tortillas directly over a low gas flame for a few seconds per side, or warm in a dry skillet until pliable.
Keep them wrapped in a clean towel.
Assemble the tacos: Spread a little sauce on each tortilla. Add a handful of slaw, a few pieces of crispy cauliflower, and avocado slices. Drizzle more sauce on top and finish with lime juice.
Add pickled onions, cotija, or hot sauce if you like.
Serve right away: Cauliflower stays crispiest just after roasting, so assemble and eat promptly for the best texture.