Heat the olive oil in a large saucepan over a medium heat and add the onions and fennel. Cover the pan, reduce heat to medium low and leave to cook gently for about 25 minutes, stirring occasionally, until soft and translucent.
Stir in all the remaining ingredients except the monkfish and the coriander leaves. Bring to the boil over a high heat, then reduce the heat to medium low, recover the pan and simmer gently for 1 hour to obtain a nice broth. Top up with a few tbsps water if it looks too dry at any point.
Add the monkfish to the pan, recover and cook for 17-20 minutes until it is cooked through. Check seasoning.
Garnish with chopped dried apricots and coriander leaves and serve immediately with couscous.