First of all, make sure that your fishmonger has skinned the fillets (it's a little more difficult with monk fish than with other fish). Place the fillets into a large pan of salted water and add the juice of both lemons. Bring to the boil then reduce the heat and allow to simmer for 15-20 minutes.
Remove the fish and take away any remaining signs of skin. Gently break the monkfish flesh into pieces about 2" (5cm) big. Above all, do NOT crumble the fish. Leave to completely cool.
In a bowl, beat one egg, then add the tomato purée (tomato paste). Add the other eggs, one at a time, while beating. Mix in the spice and then add the cooled monkfish pieces.
Using a cooking tin of your choice - either a 10" (25cm) circular ring tin like us, or a 9"x5" (22.5cm x 12.5cm) oblong loaf tin (right) - butter the inside lightly to prevent the terrine from sticking, then pour in the fish and egg mixture.
Cook in a bain-marie in a preheated moderately hot oven (Mk 7 - 425ºF - 220ºC) for 40 minutes without covering. If this sounds complicated, it's not!!! A bain-marie is simply a water bath used for gentle cooking (or for keeping food warm). The dish or tin in which the food is to be cooked is placed in a larger container (we often use a large roasting tin) containing hot water. This is maintained at just below simmering heat. So, to put it simply, pour about 1" (2.5cm) of boiling water into a large roasting tin (big enough easily to accommodate your chosen cooking tin) then place your terrine tin into the water bath and allow to cook.
After cooking, remove the terrine and check it is cooked by inserting a knitting needle (or similar). If the needle comes out clean, the terrine is cooked. If not, give it another few minutes in the oven. Turn the terrine out onto a plate and place in the fridge overnight.
Serve cold with a light, crispy salad and a bowl of mayonnaise. You can garnish with hard-boiled eggs, prawns, slices of lemon or avocado etc, if you wish.
** Some fishmongers don't offer monkfish fillets - only whole tails (complete with bone). In this case, purchase ½ lb (250g) extra, to allow for the weight of the bone, and cook the fish complete with the bones. You can then easy separate flesh and bone after cooking.