Prepare the Oven or Grill: If roasting, preheat your oven to 425°F (218°C) and line a large baking sheet with parchment paper for easy cleanup. If grilling, preheat your grill to medium heat, ensuring the grates are clean and lightly oiled to prevent sticking.
Slice the Cauliflower into Steaks: Remove the outer green leaves and trim the bottom stem, being careful not to cut too deep into the core. Place the cauliflower head upright and use a sharp knife to cut it into thick slices about ¾ inch thick. You’ll typically get 2 to 3 intact "steaks" from each head—any remaining florets can be roasted separately or saved for another dish.
Make the Seasoned Oil Mixture: In a small bowl, whisk together the olive oil, paprika, garlic powder, salt, and black pepper. This bold, smoky blend adds beautiful color and flavor to the cauliflower without overpowering its natural taste.
Season the Cauliflower Steaks: Lay the cauliflower slices flat on the prepared baking sheet or a platter (if grilling). Using a silicone brush, generously coat both sides of each steak with the seasoned oil, making sure the spices reach into the crevices for full flavor.
Cook the Cauliflower Steaks: For Oven Roasting: Place the baking sheet in the preheated oven. Roast for 10 minutes, then gently flip each steak and roast for an additional 10 to 15 minutes, or until the edges are golden brown and the stems are fork-tender.
For Grilling: Carefully transfer the cauliflower steaks to the grill. Close the lid and cook for 5 minutes. Flip each steak, close the lid again, and grill for another 4 to 5 minutes, or until nicely charred and tender.