Instructions: Set the oven to 425F 220C and heat it up. Cut the cauliflower head into "steaks" that are about an inch thick. Add salt and pepper to the cauliflower steaks and brush both sides with olive oil. Put the cauliflower steaks on a baking sheet that has parchment paper on it. After the oven is hot, roast the food for 25 to 30 minutes, flipping it over halfway through, until it is soft and golden brown. Add sriracha sauce to vegan mayonnaise and mix it in a small bowl while the cauliflower roasts. This will make spicy mayonnaise. Warm up the burger buns. Put some spicy mayo on the bottom half of each bun. Put a cauliflower steak that has been roasted on top of the mayo. Add pickles, tomato slices, lettuce leaves, and red onion slices on top. Put the top half of the bun on top. Serve right away and enjoy!