Peel the aubergines (the peel remains tough when it is grilled) and cut them into rounds about 1cm/1/3in thick. Dip them in olive oil, turning them over, and sprinkle with salt.
Cook on a griddle pan or under the grill, turning them over once, until they are lightly browned. They do not need to be very soft, as they will cook further in the sauce.
In a wide saucepan or frying pan, fry the garlic in 2 tbsp of the oil for seconds only, stirring, then take off the heat. Add the ginger, cumin, cayenne or chilli powder, honey, lemon juice and water.
Put in the aubergine slices and cook over a low heat, either in batches so that they are in one layer, or together - rearranging them so that each slice gets some time in the sauce - for about 10 minutes or until the slices are soft and have absorbed the sauce. Add a little more water if necessary to thin sauce.