Place the dried mushrooms in a bowl and cover with boiling water. Leave to soak for 10 minutes.
Meanwhile, heat the oil in a large frying pan. Add the aubergines and onion and fry gently for 8 minutes until the vegetables are softened and browned.
Drain the dried mushrooms and add to the pan with the cumin seeds, fresh mushrooms and garlic. Fry for a further 5–7 minutes until the aubergines are very soft.
Transfer the mixture to a food processor or blender with the pickled walnuts and coriander, season to taste with salt and pepper and process until broken up but not completely smooth. Transfer to a serving dish and chill until required. Serve the pâté on thick slices of bread or hot toast.