Arrange the aubergine slices in the base of a tagine or a large, heavy-based saucepan and scatter over the spring onions, chilli and ginger. Place the fish chunks on top.
Pour over the vinegar and measurement water and season with salt and pepper. Bring to the boil, then reduce the heat, cover and cook gently for 25–30 minutes until the fish is cooked through. Garnish with the parsley and serve with couscous, if liked.