For the curried lentils, place the grated ginger in a clean towel or a piece of muslin, over a small bowl, and twist the cloth to extract the juice. Set aside.
Heat the olive oil in a frying pan and fry the carrot, celery and leek 4-5 minutes, or until the softened.
Add the garlic and cook for a further minute. Stir in the curry paste, reserved ginger juice, lentils and chicken stock. Bring the mixture to the boil, reduce the heat and stir in the tomatoes, coriander and crème fraîche.
For the monkfish, season the monkfish slices, to taste, with salt and freshly ground black pepper and pour over the lemon juice.
Carefully stir the monkfish slices into the curried lentils and heat gently for 2-3 minutes, or until the fish is cooked through.
To serve, spoon the monkfish and curried lentils into each of 4 serving bowls. Sprinkle over the chopped coriander.