Preheat oven to 180°C. Cut the base of the cauliflower so it sits flat on an even surface. Cook in a steamer over a saucepan of simmering water for 10 mins. Transfer the cauliflower to a roasting pan. Combine oil, harissa paste and cumin seeds in a bowl. Brush oil mixture over cauliflower and cover with foil. Roast for 30 mins. Remove foil. Roast for 20-25 mins or until just tender.
Meanwhile, place the macadamias in a saucepan with 4 cups (1L) water. Bring to a simmer over medium-low heat. Cook for 30 mins or until the macadamias soften. Drain, reserving 1/2 cup (125ml) cooking liquid.
Place vinegar, maple syrup, sea salt flakes and ¼ cup (60ml) water in a small saucepan. Bring to a simmer over low heat. Place currants in a heatproof bowl. Pour over the vinegar mixture. Soak for 20 mins. Drain, reserving pickling liquid.
Blend the drained macadamias, tahini, garlic, reserved cooking liquid and ¼ cup (60ml) pickling liquid in a blender until smooth and creamy.
Spread the macadamia mixture over a serving plate. Top with the cauliflower. Sprinkle with currants to serve.
Tip: SERVE WITH... toasted chopped macadamias, toasted sesame seeds and flat-leaf parsley sprigs