Preheat oven 220°C fan forced. Combine mushrooms and sweet potato in a large roasting pan. Sprinkle over spice blend. Drizzle with oil, season with pepper. Turn to coat. Roast 40 minutes until light golden and tender.
Remove the centre stem from the kale, roughly chop leaves. Scatter them over the sweet potato and mushrooms. Spray lightly with oil and roast 5 minutes. Remove from the oven.
Meanwhile cook the rice and quinoa following packet directions. Transfer to a bowl. Pour the dressing over the warm rice. Add currants and stir to combine.
Just before serving stir the rice and cashews through the kale and roast vegetables. Serve warm, cold or at room temperature.