Thinly sliced cauliflower florets mimic the signature shape of fajita meat in this dish. We cook it in a cast-iron skillet for that tableside sizzle you'd get at a restaurant.
Position a rack in top third of oven and place a large cast-iron skillet on it. Preheat to 425°F.
Combine cauliflower, bell pepper, onion and oil in a medium bowl and toss to coat. Sprinkle with chili powder, cumin, coriander, salt and pepper and toss until well coated. Carefully add the mixture to the hot pan. Roast, stirring once, until the vegetables are tender, about 30 minutes.
Set broiler to high. Broil the vegetables until lightly browned, about 2 minutes.
Top the vegetables with pico de gallo, jalapeños and cilantro, if desired. Serve with refried beans and tortillas.