To make the pilaf, brush the aubergines with 2 tbsp of olive oil and heat a griddle pan to high. Grill the aubergine slices for 1-2 minutes on each side or until deeply charred and starting to soften. Season and remove onto a plate. Heat the remaining oil in a large pan and add the onion, ginger, garlic, chilli and spices, and cook gently for 10 minutes or until soft. Tip in the rice and mix really well. Season and pour in the stock. Bring to the boil, then turn down to a gentle simmer. Add the tomatoes in a layer on top, and then the aubergine in another layer. Put on a tight-fitting lid and simmer gently for 12 minutes until the rice is cooked and the aubergines and tomatoes are tender.