Surrounded by the Atlantic Ocean to the west, the Celtic Sea to the south and the Irish Sea to the east, Ireland enjoys a coastline rich with seaweeds that have numerous health benefits. Of these, the red algae called Palmaria palmata, or dulse, holds a special place in Irish life.

High in minerals, vitamins and trace elements, dulse has been important part of the Irish diet for centuries. Also called dillisk, this seaweed is said to have more minerals than land plants. It was the go-to food in Ireland during the Great Famine in the 1840s. Easily harvested along the coast from March to September, the algae is dried for few hours before being packed in bags and sold in vegetable shops and supermarkets.

“Based on the tide time, I harvest the dulse early morning along the County Down coast between Donaghadee to Portavogie. I get back, say, 8am, dry it for maybe three hours and then turn [it over] for another three,” says 68-year-old Alan Coffey, a fishmonger at St George’s Market in Belfast. “You have to watch the forecast. If you get showers, the dulse is destroyed.”

During low tide, as the seawater recedes, the translucent fronds cling to the rocks, making it easy to harvest, a process called “dulsing”. This practice is said to date back some 1,400 years ago, to the time of Saint Columba.

Rhatigan, who refers to the seaweed by its Gaelic name duileasc, with a rolling “l” sound, has a section, Memories of Duileasc, in her book Irish Seaweed Kitchen. She says the comprehensive set of Irish laws called the Brehon Laws, laid down in the fifth century, had a section which has mentions of duileasc being served along with bread, whey milk and butter.

She ate seaweed as a child at the recommendation of her doctor father – and says dulse would be given to children suffering from thread or pin worms. (The Irish have another medicinal use for seaweed too – seaweed baths, which are said to do wonders for your hair, skin and joints.)

Today dulse is popular in Ireland with middle-aged and elderly people. “I have it maybe twice a week. You can catch me watching television on a Saturday night with a bag of dulse and a glass of wine,” Coffey says.

Andy Rae, executive chef of Mourne Seafood Bar, in Belfast, is 46, and has vivid childhood memories of dulse. “When I was a boy, they had these corner shops before the advent of supermarkets. A bag of dulse from these shops was like eating a bag of chips. It was almost like our street food,” he says.

Coffey adds: “When deep fried it comes out green and very crispy and nice.”

At Sawers, a delicatessen that has been in Belfast since 1897, a 100-gram bag of dulse is sold for a little more than £1 (US$1.20). “My septuagenarian granny loves to have dulse sandwich – butter and dulse on bread,” says Kieran Sloan, 23, manager at Sawers.

“Many years ago, with the Troubles [in Northern Ireland], it was one of those foods which was easier for people with less access to money. It is cheap, nutritious and delicious,” he says. “It was fit for the working class, like a peasant snack.”

Billy Scott, our fifty-something tour guide from Belfast, jokes: “Dulse gets you thirsty, hence is best enjoyed with beer. Water has toxins so better to avoid.”

Sinead McKendry, a Belfast food tour guide, says: “As a kid I have watched my mother nurse her hangover with a bag of dulse the next morning. It probably has to do with the salt levels in it.”

In recent years Irish chefs and artisans have been working with dulse, bringing new life to the seaweed.

Dulse butter is an example of that. Milled seaweed, with its natural salt, is mixed with freshly churned butter, and sold under the Abernethy brand.

And at Hadskis, a restaurant in Belfast, I relished smooth and creamy seafood chowder with squid accompanied by romesco sauce. But the star of the dinner was the perfectly cooked Irish hake with smashed celeriac and dulse gremolata.

“The texture of fresh dulse is like cold pasta. You can chop it and add it to pasta like a vegetable. Dulse can be used in dressings and seasonings. It goes well with pork stews and soups,” says the restaurant’s executive chef, David Gillmore. He also recommends adding it to flour when making bread.

Rhatigan’s book lists many dishes containing the seaweed, including soda bread baked with dulse, carrot and duileasc loaf, scones with dulse, and duileasc ice cream.

One of the oldest surviving dulse experiences can be had at the Ould Lammas Fair, held on the last Monday and Tuesday of August every year in Ballycastle, Northern Ireland, since 1606. Here stalls sell dulse in different forms, including with yellowman, an Irish honeycomb toffee. “Have you heard the Ould Lammas Fair country song? It has references to dulse and yellowman,” says Scott, breaking into song.

The younger generation of Irish haven’t taken to dulse as their parents and grandparents did, however. “I think it’s because we’ve been brought up with access to other types of foods throughout the world. We’re in a better time now in terms of the economy so we can go out and afford to buy different things,” Sloan observes.

When I tasted the seaweed from a bag bought at a greengrocer’s in Belfast, I found it salty, dry and chewy. I realised that, like wine or whisky, it is a taste that needs to be acquired.

Rae says: “It’s like chewing tobacco – you keep chewing and you get the taste of the sea, but it’s quite sort of salty. It’s got a heavy texture too.”

Despite Rae’s caution, I cannot help buying a bag of the stuff as a souvenir to take back home.