A one-dish supper of buttery mashed potatoes and greens

"The poorest man in Ireland knows what good potatoes and butter are," Peter Ward told me last spring at Country Choice, his café and market in Nenagh, midway between Dublin and Kerry in County Tipperary. "They're here for everybody." Ward, a big, friendly man who could have succeeded as a busker, speaks memorably about his mission to save and serve great farmhouse food—and, as an admiring friend told me before I visited, "he doesn't draw breath."

Country Choice is a "railroad car of a shop," as Ward says, behind an unassuming façade in a small town of extreme charm that somehow manages to skirt self-consciousness. The restaurant, which serves breakfast, lunch, and tea every day except Sunday, is a generous room up a few stairs at the back. There I learned about a potato dish with the appealing name of champ.

Nenagh was once the site of an important cattle market, and is still an important crossroads. ("It's hard to describe the Irish relationship with the cow," Ward says. "It's not unlike the Masai.") The town's dairy business remains strong: a large cooperative behind the shop produces butter for export to Europe. Farmhouse cheese has joined smoked salmon as Ireland's calling card in the world of gastronomy, and Ward ages the selections he brings home from his visits to cheese makers. The morning I visited, a Country Choice worker had gone to the bus stop to retrieve a round of Cashel blue, a mild but authoritative cow's-milk cheese. Jane and Louis Grubb, the Tipperary farmers who created Cashel blue, had entrusted the cheese to the bus driver, who knew both them and Ward. ("Food production in Ireland survives on friendship.")

Ward, who grew up on a farm in County Meath, opened his shop in 1982 after marrying Mary D'Arcy, who had grown up on a Nenagh farm. He began going to agricultural shows and calling on local farmers and cooks, and advertised in local papers saying that he would happily buy excess fruit, vegetables, and eggs. A welcome source was the kitchens and gardens of the Palladian villas around Lough Derg, a lake formed by the River Shannon that draws many tourists; two centuries ago the second sons of Anglo-Irish families with large inland estates built the houses, which are now largely the retreats of merchant princes. Peter began selling chutneys (a legacy of the Raj), from the great kitchens' annual production, and Mary began putting up jams and jellies with the "buckets and buckets" of damson plums, gooseberries, and other fruit gardeners brought by. Now she makes 15,000 jars a year.

The buckets of berries, and dripping crates of lettuce, and sacks of potatoes all arrive through the front door. Ward encourages what he calls the French practice of buying from the top of the counter and the supplies meant for the kitchen rather than from the glass case and the shelves. When I visited, customers were vying for the season's first fat asparagus. ("With our eggs and our butter they can make the mother and father of all Hollandaises.")

As we spoke, I was finishing a second helping of rhubarb crumble, made with rhubarb Ward had brought in that morning from his garden at the stone millhouse he shares with Mary, their three children, and five dogs. The crumble was a great example of its form (no oatmeal or nuts or trick ingredients in the crisp topping), but the real reason I had to have seconds was the cream on top—unwhipped and unclotted but still so thick you could faint from it. This was after a vegetable soup with a strong homemade chicken stock as its base and carrots, leeks, onions, and potatoes from local farms (I had a second helping of soup, too).

The bacon that makes its way into many dishes, the small tongues to be boiled and sliced for sandwiches, and the beautiful racks of beef I saw roasting in the glass-doored oven are also points of pride with Ward. Sophia O'Dowd, the confident young cook, said that only recently, two years after she began work, with two years of experience and a culinary-college degree to her credit, has Ward let her bake a ham. O'Dowd told me that the ingredients she could work with at Country Choice, and the freedom Ward allowed her (except with ham), were "Aladdin's keys for any chef."

Champ also goes by other charming names: stelk, cally, poundies, pandy, and, in Gaelic, brúitín. The principle is to simmer scallions or the greens from new onions in milk, beat the hot milk into just-mashed potatoes, and serve the potatoes mounded on hot plates with a well in the center for a lump of butter. Champ is nowadays served as a side dish, but it was traditionally an entire meal, frequently eaten on Fridays and fast days.

Here is a recipe—using tips from O'Dowd and a basic recipe from Myrtle Allen, whose Ballymaloe House restaurant and inn, in County Cork, launched several generations of cooks—to serve four as a main meal or six as a side dish. Allow a stick of butter to come to room temperature. Simmer two pounds of scrubbed, unpeeled, whole yellow-fleshed potatoes (see "Maine Certified," for suggested varieties) in salted water for thirty to forty minutes over medium heat; don't let the water boil. While the potatoes cook, simmer over low heat and in a separate pot one and a half cups of whole milk with a cup of fresh onion greens or scallions, chopped into rough half-inch lengths, until the greens are softened. Scallions are traditional, but you can use any greens you like; chopped fresh spinach leaves seem ideal to me, because I grew up in a house where mashed potatoes and spinach was a favorite Sunday supper. Frequent Irish variations include the same quantity of nettles or baby peas; a quarter cup of any fresh green herb, such as chives, parsley, or watercress, can be substituted. Strain out the greens when cooked, and reserve both the greens and the milk.

When the potatoes are tender all the way through (pierce them with a skewer or a knife), drain and, if you wish, peel them. Return the potatoes to the pot and dry them over medium heat for a minute or two, keeping them moving with a wooden spoon so that they don't stick. If the milk has cooled, heat it again just to a simmer. Mash the potatoes as you prefer: a ricer is the easiest and best way, and I also like old-fashioned wire-bottomed mashers (grid bottoms overwork the potatoes). As soon as the potatoes are free of lumps, add salt and pepper to taste and beat in a cup of the hot milk in a slow stream. Add more milk depending on how loose you like your potatoes, and stir in the greens until well blended. Spoon the potatoes onto hot plates and make a well in the middle of each serving. Pass the butter, so that each diner can cut a pat and watch it melt in the well. Don't skimp on the butter. It's part of the Irish glory.