Food: The sea, the sea

Annie Bell is transported to the shore by the savour of seaweed

Sitting on a windswept patch of lawn in the Outer Hebrides sharing a bowl of lime jelly with a Catholic priest was about as surreal as it sounds. And tempting as it is to expand on the colourful character of the priest, who lived mainly off what he could scavenge from the shore or grow in the inhospitable clime of the garden, the real reason I introduce the event is the jelly.

This was a milky lime green and set with agar agar that he had harvested from the nearby beach. You may yourself have dabbled with this seaweed derivative; I have done and have also given up on it as a poor substitute for gelatine, but this particular jelly was memorable.

In any case, agar agar was just one of the strange maritime plants to be found in the priest's vegetable rack, and I was impressed, if not entirely convinced, by the notion of seaweeds as food. On the same holiday, I also found myself hesitantly nibbling on oarweed chips by way of an appetiser.

These are made from the bulky brown racks with wavy edges that lie on the line left by the last tide. Collecting and cooking oarweed seemed to hold particular appeal for the male contingent of the holiday as they dragged the massive, ruffled streamers off the beach, threw them into the boot of the car and transported them home. There, under the guidance of Roger Phillips's Wild Food, they fried up chips: "Collect a nice, fresh frond of oarweed, and leave it hung up in the kitchen to dry, then cut it into squares and fry it in a light oil. The squares will expand very quickly and start to brown. Remove them after a few seconds and drain on kitchen paper."

In the end, the chips received a double frying, as this seemed to do them more justice than the original recipe, but, really, they weren't at all bad and fitted comfortably into the rough-and-ready maritime scene. If you're not entirely convinced, you're not alone. In the Scottish Wayfarers' Book, written in 1936, the authors give a recipe for seaweed that they recommend "you offer to those who really love you. They are the only people, yourself excepted, who are likely to eat it."

Eating seaweeds (or sea vegetables to give them more status) is not hugely to our taste. Heaven knows, they have strewn our beaches prolifically for many centuries and there's no great rush on them other than in Wales, where laver bread and oatmeal make up a breakfast-time treat along with a little crispy bacon.

So I find it surprisingly brave of Tesco to have taken the plunge in stocking fresh sea lettuce (Ulva lactuca) and dulse (Palmaria palmala). The sea lettuce is true to its name, only prettier - a mass of filmy lobe- shaped fronds that are a deep luminescent green. When you wash it of its coating of rock salt, the scent that drifts out of the sink is of pure harbour at low tide. And the dulse, normally found between tide marks hanging from rocks and racks of oarweed, is a mass of mauve ribbons with much the same iodic quality.

Being suspicious of foods sold on their nutritional benefit rather than their quality as a foodstuff, I have long held seaweeds at arm's length in healthfood shops and Japanese emporiums, not least because I don't know what to do with them and the packets are less than helpful.

To my way of thinking, sea lettuce and dulse fall somewhere between a herb and a vegetable. Neither can be sold on texture, which belies their delicate appearance - they look far more alluring than they chew. If you consider a life of being buffeted underwater, the necessary resistance and toughness of the frond is logical.

Their attraction is quite simply the scent of sea shore. Mussels, oysters and sea urchins transport you straight to the seaside, seaweeds likewise. If you can conjure up toasted strips of nori scattered over noodles or a deep bowl of ramen, or, for that matter, the paper-thin wrapping of sushi, then you will know exactly the elusive scent I am referring to.

Best of all, they combine in a fish pie, lasagne, soup or a bowlful of mussels, using just a handful of finely sliced and sweated fronds. And it needn't be anything grand off the slab, a modest collection of white fish gains dramatically from their flavour.

But to end with a little irony, Tesco is sourcing their seaweeds in Brittany. Quite why, when our own shores are lavished with the stuff, I cannot imagine, although it does refer to the "local group of pickers who are able to distinguish one weed from another". Perhaps that's it, we have yet to recognise our dulse from our sea lettuce.

Fish Pie with Seaweed, serves 8

In the finest tradition, you can't beat frozen peas with this.

Fish:

2 fennel bulbs

75g/3oz unsalted butter

50g/2oz sea lettuce, rinsed and finely sliced

sea salt

freshly ground white pepper

150ml/5 fl oz white wine

110g/4oz Tiger prawns, cooked, peeled and sliced

570ml/1pt fish stock

800g/134 lb monkfish, cod, sole and halibut, filleted, skinned and sliced

40g/112 oz plain flour

150ml/5 fl oz double cream

Mashed potato:

1.4kg/3lb maincrop potatoes, ie Maris Piper, King Edward, Desiree, Pentland Crown

75g/3oz unsalted butter

50ml/2 fl oz milk

sea salt

freshly ground white pepper and nutmeg

2 medium egg yolks

Cut the shoots off the fennel bulbs and remove outer sheaves if they are damaged or very tough; dice remaining bulbs. Heat 25g/1oz of the butter in a medium saucepan and sweat the fennel and seaweed for several minutes, seasoning it, until the fennel is soft and translucent. Add the wine and cook until it reduces to a syrup. Transfer the vegetables to a casserole or pie dish and add the cooked prawns.

Bring the fish stock to a simmer in the same pan and poach the white fish for three minutes - do this in two lots. Remove fish with a slotted spoon and add to the vegetables. Reduce the fish stock to 150ml/5 fl oz.

Heat the remaining butter in another saucepan, add the flour and cook for a minute until the roux dries out. Remove from the heat and gradually beat in the fish stock and the cream. Add any juices given out by the fish and vegetables, as well. Simmer the sauce very gently for five minutes, seasoning it to taste, then blend with the fish and vegetables.

To make the mashed potato, bring a large pan of salted water to the boil. Peel the potatoes and cut into the same size. Boil until tender, then drain and leave in the sieve until the surface water evaporates. Pass them through the sieve or a mouli-legumes. Heat the butter and milk together and blend with the potato. Season and add the egg yolks.

Spread the potato over the fish and vegetables and fork the surface. Cook the pie for 30 minutes at 190C (fan oven)/200C (electric oven)/400F/Gas 6