Heat 2 tbsp oil in a pan, add the onion and fry until soft and lightly browned, about 10 mins. Add the chilli, ginger and spices and mix well. Stir in the chickpeas, tomatoes and 5 tbsp water, bring to the boil, then simmer for 10 mins. Add a little salt and pepper and the lemon juice.
Arrange the aubergines over a grill pan. Brush lightly with oil, sprinkle with salt and pepper, then grill until golden. Flip them over, brush again with oil, season and grill again until tender and golden.
Mix the yogurt with the garlic, most of the walnuts and coriander and a little salt and pepper. Arrange the aubergine slices over a warm platter and spoon over the chickpea mix. Drizzle with the walnut sauce and scatter with the remaining walnuts and coriander.
4 tbsp olive oil
1 onion, finely chopped
1 red chilli, deseeded and finely chopped
2cm piece ginger, finely chopped
½ tsp each ground cumin, coriander and cinnamon
400g can chickpeas, rinsed and drained
200g tomatoes, chopped
juice ½ lemon
2 aubergines, sliced lengthways
For the walnut sauce
200g tub Greek-style yogurt
1 garlic clove, crushed
25g walnuts, chopped
handful coriander leaves, roughly chopped