Shell the broad beans and cook them in lightly salted water for 15 minutes. Refresh them and then drain them and remove the green skin covering each bean. Cut the lemons into quarters.
Heat 4 tablespoons olive oil in a pan. Place the cod steaks skin side down and cook them for 10 minutes over a medium heat, turning them halfway through the cooking time. Season with salt and pepper.
While the fish is cooking, put the broad beans and the lemon quarters in a frying pan and season. Pour on 2 tablespoons of olive oil and reheat over a very low heat. Wash and dry the chervil.
Place a cod steak on each plate and add the broad beans and lemon. Decorate with sprigs of chervil and serve immediately.