Ingredients to serve 6

Small bunch of fresh rosemary, roughly chopped
2 tablespoons coarse sea salt
20 medium-sized potatoes, scrubbed
1 preserved lemon (see below), cut into 12-16 wedges
2 tablespoons olive oil, plus extra for cooking
freshly ground black pepper
6 halibut slices on the bone, weighing about 225-300g each
juice of 1 lemon
leaves from 3 sprigs of fresh parsley, roughly chopped

For the preserved lemons

2 lemons
3 heaped tablespoons sea salt
olive oil, for preserving

First make the preserved lemons. Place the lemons in a small pan in which they fit tightly and cover with cold water. Add the sea salt – it takes the bitterness out of the lemon skin. Bring the water to the boil and simmer until the lemons are soft to the point of a knife.

Remove from the hot water and refresh under cold running water. Put the lemons in a sterilised jar (reserve one for this recipe) and cover with olive oil; they will keep, covered, in the fridge for up to six weeks.

Preheat the oven to 180C/gas mark 4. Place the rosemary in a pestle and mortar with the salt. Grind until you have a green-coloured salt, then sieve it to remove the stalks, leaving a pale green fine salt.

Cut each potato into three even-sized chunks. Mix with the lemon wedges and olive oil and season well with black pepper and half of the rosemary salt. Spread the herbed potatoes and lemon mix in one layer in a large roasting tin. Roast for about 35 minutes, turning a few times so that they begin to brown.

Preheat a griddle pan. Oil the fish on both sides and season with black pepper and the remaining rosemary salt. When the griddle pan is really hot, grill the fish for two minutes on one side until the skin is beginning to crisp. Carefully turn the fish over and cook for a further two minutes.

Gently remove the fish from the griddle pan and lay it on top of the roasting potatoes. Return the roasting tin to the oven and bake for 10 minutes until the fish is cooked and the potatoes are browned. When the fish is cooked, add the lemon juice and the parsley.

TIP: This flavoured salt will keep for about a week in an airtight jar; it is good with roast meat as well as fish and potatoes. You could make a similar salt using fresh bay leaves instead of rosemary.

From 'Fish Tales' by Bart van Olphen and Tom Kime (Kyle Cathie, £19.99)