Rub ½ tsp salt into the aubergines and leave them to drain in a colander for 30 minutes.
Put the chickpea flour, cumin seeds and coriander seeds into a heavy frying pan and toast on a medium heat until the seeds pop and the flour becomes darker. Scoop out into a pestle and mortar and roughly crush the seeds. Add the ginger, garlic, cayenne, paprika, fresh coriander, ½ tsp salt and bash into a thick, sticky paste.
Pat the aubergines dry with kitchen paper, then rub the paste into them.
Put the oil in a large frying pan. When it is hot add the aubergines and begin to fry, browning them on all sides for 3 or 4 minutes. Add 3 tbsp water. Pop a lid on the pan and leave to simmer for around 15 minutes.
Whisk the lemon and sugar together and pour over the aubergines. Continue to cook for a few minutes, turning them once, until there is a thick sauce and the aubergines are almost falling apart. Serve warm, topped with chopped coriander.