Wash and drain the leek. Place the lentils in a casserole dish and cover with the stock. Add one of the bay leaves and bring the mixture to a simmer over a moderate heat.
Reduce the heat to low then sit the batons of carrot and the leek on top of the lentils.
Cover with a lid and reduce the heat. Simmer for 20 minutes until the lentils and the carrot are tender. Meanwhile, cut the leek into 4 even pieces and season with salt and black pepper.
Sit the pieces of haddock on top of the leek and carrot and cover again with a lid.
Steam for 3-4 minutes until the haddock is just cooked.
Spoon the lentils into serving bowls and top with a mixture of the carrot and leek. Sit the haddock on top and garnish with a bay leaf, a sprig of dill leaves and a little more black pepper before serving.