For the aubergine, preheat the oven to 180C/350F/Gas 4. Put the aubergines over an open flame and burn the skins. When scalded all over, place the aubergines on a baking tray and bake in the oven for 35-40 minutes, or until cooked. Remove the aubergines from the oven and leave to cool.
When the aubergines are cool, cut them down the middle and scoop out the creamy flesh – taking care not to pick up any of the toasted black skin. Using a sharp knife, chop the aubergine until it forms a rough purée. Transfer to a sieve set over a large bowl and leave to drain in the fridge overnight.
Toast the cumin and coriander seeds, either in a dry frying pan set over a low heat or in an oven preheated to 180C/350F/Gas 4 (this will take 8-10 minutes). When toasted, remove from the heat and leave to cool.
Blend the toasted seeds in a spice grinder to form a powder. Pass through a fine sieve to remove any bigger pieces.
Heat a little olive oil in a saucepan and stir in one and a half tablespoons of the toasted spice powder. Cook for 2-3 minutes. Stir in the drained aubergine and, when hot, add the double cream, lemon zest and a splash of the lemon juice and season to taste with salt and pepper. Stir through and set aside.
Dust the monkfish fillets in the remaining spice mixture. Heat a splash of olive oil in a non-stick frying pan set over a medium heat and cook the fillets for 6-8 minutes, turning all the time so that the spices do not burn. Remove from the pan and baste the fish in melted butter and a squeeze of lemon juice. Set aside to rest.
To make a dressing, finely chop the green olives, capers, anchovies and red chillies. Mix together in a large bowl with the olive oil, remaining lemon juice and chopped parsley. Season to taste with salt and pepper.
To serve, reheat the aubergine purée, if necessary, and place a spoonful on each plate. Slice the monkfish and place on top with the dressing spooned over. Garnish with the celery leaves.