Place the 1/2 cup olive oil, the onion, garlic powder, Italian seasoning, and cayenne pepper in a medium bowl. Add salt and black pepper to taste and the lemon juice. Whisk to combine. Transfer to a shallow pan.
Using a large chef’s knife, cut off the cauliflower stems flush with the head. Place the stem ends down on a cutting board. Slice each cauliflower in half. Then cut into slices ½ to 1 inch thick (steaks).
Turn on the exhaust fan if cooking indoors. Heat the grill to medium, or place a grill pan over medium-high heat on the stove top. Using tongs, dip the cauliflower steaks in the marinade.
Place on the grill or grill pan and cook 5 to 8 minutes per side, until browned on the outside and tender inside. Transfer to a serving platter. Adjust the seasonings and serve with as much olive oil as you like.
Source: https://gundrymd.com/cauliflower-steak-recipe/ VARIATION: Roasted Cauliflower Steaks with fresh Gremolata: 5. While cauliflower is baking, combine remaining 2 tsp. oil, chopped lemon, parsley, shallot, garlic, remaining ¼ tsp. salt, and remaining ¼ tsp. pepper in a medium bowl; mix well. 6. Top each cauliflower steak with 1 heaping tsp. of lemon mixture. Source