Tip the rice into a pan of boiling water and cook for 12 mins until only half cooked. Drain, but reserve the water. Meanwhile, heat the oil in a large non-stick pan that has a lid, and fry the onion over a medium heat until golden. If it starts to catch, cover with the lid.
Tip in the carrots and cauliflower, and continue cooking, covered, for 5 mins. Stir in the curry powder, cinnamon and cumin seeds, the ginger and garlic. Stir well. Tip in the rice, add 2 tbsp of the yogurt and pour in 300ml of the reserved rice water mixed with the bouillon powder. Stir in the cashews and peas. Cover and cook for 10 mins over a gentle heat until the rice is tender and all the liquid has been absorbed. Add half the mint and half the coriander, then leave to rest for 5 mins.
Meanwhile, make a raita by stirring the remaining mint and coriander into the remaining yogurt, then add 1 tbsp cold water to loosen – you can whizz together with a hand blender if you want a green raita. Spoon into small bowls to serve alongside the biryani.