Pan-Seared Harissa Cauliflower Steaks with Whipped Feta and Pistachio Gremolata

["Preheat your oven to 200°C (180°C fan/Gas Mark 6). Line a baking tray with baking parchment.","Prepare the cauliflower by removing the outer leaves and trimming the stem so the cauliflower can sit flat. Carefully cut the head vertically into two thick (about 2.5cm thick) centre 'steaks'. The outer florets will fall away; reserve these for roasting alongside the steaks.","Prepare the Harissa Marinade: In a small bowl, mix 30ml of olive oil, the Harissa paste, smoked paprika, 1 tsp of cumin seeds, 1/2 tsp of salt, and a grind of black pepper.","Place the cauliflower steaks and the reserved florets on the prepared baking tray. Brush both sides of the cauliflower generously with the Harissa marinade, ensuring the marinade gets into the crevices.","Roast for 25-30 minutes, flipping halfway through, until the steaks are tender when pierced with a fork and slightly charred at the edges.","Prepare the Whipped Feta Base: While the cauliflower roasts, combine the feta cheese, Greek-style yogurt, lemon juice, and 10ml of olive oil in a food processor or use a stick blender. Blend until completely smooth and creamy. Season with a small pinch of salt if needed.","Prepare the Pistachio Gremolata: Roughly chop the pistachios and parsley together. Mince the garlic clove finely. In a small bowl, mix the chopped pistachios, parsley, minced garlic, the remaining 1 tsp of cumin seeds, and a drizzle of olive oil (about 5ml). Adjust seasoning with a pinch of salt.","To serve, spread a generous layer of the whipped feta base across the base of two serving plates.","Carefully place one hot cauliflower steak on top of the feta base.","Spoon the pistachio gremolata evenly over the top of the steak.","Serve immediately."]