Cooking with Seaweed: A Gentle Introduction for Home Cooks

Why Seaweed Belongs in a British Kitchen

Walk any stretch of our coastline at low tide and you are standing in a larder. Seaweed has been eaten around these islands for centuries — in Wales, Ireland, Scotland and the West Country it never entirely went away — and it is quietly returning to British plates. The appeal is simple. It is richly savoury, it adds a deep marine note that nothing from the vegetable rack can imitate, and a small handful goes a very long way. You do not need to live by the sea to cook with it, either. Good dried seaweed keeps for a year in a cupboard and rehydrates in minutes.

If you are curious but not yet convinced, start small. Three ingredients — dulse, kelp and samphire — will teach you most of what you need to know.

Meet Your Three Starter Seaweeds

Dulse is the friendly one. A reddish-purple seaweed that grows on rocks around our shores, it has a soft, chewy texture and a flavour often described as nutty, smoky and faintly bacon-like. Eaten raw straight from a reputable supplier it is pleasant enough, but dried and crisped in a dry frying pan it becomes something else entirely — a genuinely delicious thing to crumble over potatoes or scrambled eggs.

Kelp, including the long ribbons sold as kombu, is the umami workhorse. It is thick, leathery and requires cooking, but it rewards patience with a savoury depth that transforms stocks, broths and bean pots. A single strip the length of your hand will flavour two litres of liquid.

Samphire is the odd one out, since marsh samphire is strictly a saltmarsh plant rather than a seaweed. It appears in greengrocers and fishmongers each summer, bright green and crisp, and needs nothing more than a brief blanch and a knob of butter. Rock samphire, the cliff-growing kind, is a different plant altogether — pleasantly aromatic but strongly flavoured, and best used sparingly.

Sourcing Well: Clean Water and Reputable Suppliers

Seaweed absorbs what surrounds it, so where it comes from matters more than it does with most ingredients.

• Buy from established suppliers who can tell you where their seaweed was harvested and who test for heavy metals, iodine levels and contaminants. This is not a fussy concern — it is the single most important buying decision you will make.
• If you forage for yourself, avoid estuaries and harbours near industrial sites, sewage outfalls, marinas and busy shipping lanes. Choose exposed, clean, fast-flowing water instead.
• Never harvest after heavy rain, when runoff is at its worst, and check local bylaws first — some areas require permission, and some are protected.
• Cut seaweed above the holdfast rather than pulling it up, take only a little from any one patch, and leave the rock attached. The plant regrows; the rock does not.
• Dried seaweed is the safer choice for beginners. It is consistent, tested, and far easier to judge.

Preparing and Storing Your Seaweed

Dried kelp often arrives with a white, chalky bloom on the surface. Do not wash it off — that is natural mannitol, and it carries sweetness. Wipe the sheets with a damp cloth if they look dusty, then rehydrate in cold water for ten to twenty minutes. Keep that soaking liquid; strain it and use it as the base of a soup or a pot of rice. It is far too good to pour away.

Dulse usually needs no soaking at all. Toast it in a dry pan over a medium heat for a minute or two, until it smells nutty and turns crisp, then crumble it. Samphire should be rinsed well in cold water to remove grit and sand, and any woody lower stems trimmed away.

Store dried seaweed in an airtight jar in a dark cupboard, where it will keep its flavour for up to a year. Fresh samphire is best used within two or three days, wrapped in a damp cloth in the fridge — or pickled in vinegar with a little sugar and mustard seed, which keeps it going for months.

Three Simple Ways to Cook With It

A broth that tastes of the shore. Put a strip of kelp, an onion, a carrot, a stick of celery and two litres of cold water in a pan. Bring slowly to a bare simmer — never a rolling boil, which turns kelp slippery and bitter — and hold it there for twenty minutes. Strain. You now have a light, savoury stock for fish stews, noodle soups or risottos.

Dulse butter. Beat a tablespoon of toasted, crumbled dulse into 100g of soft butter with a squeeze of lemon and plenty of black pepper. Roll it in greaseproof paper and chill. It is excellent melted over new potatoes, grilled mackerel or a plain baked potato.

Samphire, plainly done. Drop it into boiling water for sixty seconds, drain thoroughly, then toss with butter, lemon juice and pepper. Do not add salt — samphire is already salty enough. It makes a fine partner for lamb, crab or simply a slice of buttered toast. A spoonful of chopped dulse folded through a potato salad works on the same principle: a little, used well.

A Few Sensible Cautions

Kelp is exceptionally high in iodine, and a small serving provides a great deal of it. Enjoy it two or three times a week rather than daily, and if you have a thyroid condition or take thyroid medication, speak to your GP before making it a habit. Samphire is naturally salty, so season around it rather than with it. And if you are new to seaweed, begin with modest quantities — a teaspoon of dulse, a short strip of kelp — and let your palate tell you where to go next. Our coastline has been feeding people for a very long time; there is no rush.