The feast table does not seem fully set without a potato dish - or two. You can roll out gnocchi and brown gratins until the doorbell rings, but nothing is more satisfying than a masterful rendition of simple classics - mashed or roasted potatoes.
Mashed potatoes can be sweet, creamy, and light as air, or a wet, gluey soup. The same applies to roasted potatoes; the best are a gilded golden brown, lighter and crispier than the best french fry, while the worst are leathery as a salted pink eraser. With dishes this simple, everything matters. When these potato dishes fall short, it's hard to blame the spuds. It's usually the cook who has done something wrong.
Any starchy potato that is cooked and crushed could be called a mashed potato, but most haphazard renditions fall short of the ideal. At Petit Robert Bistro, in Kenmore Square and in the South End, chef Jacky Robert has refined the technique. "For mashed potatoes the potatoes have to be cooked perfectly," he says. "You know they are right when the knife passes freely through the flesh. If they start to break apart in the water - they are overcooked. But remember it's better to overcook than to undercook. Slightly overcooked potatoes can be dried out in the oven, but undercooked will always be like glue."
While the potatoes are still hot, Robert beats in butter. "Everything has to be done hot, in one motion," says the chef. "The more you work the gluten the looser the potatoes will be. If you really want the best, use butter and cream rather than milk." Robert uses lots of butter, about 1/2 pound for every 5 pounds of potatoes. "I'm from Normandy," says the French-born chef, "the land of butter and cheese."
Robert's method is just right for a busy restaurant but not as practical for home. Potatoes simmered slowly in their skins will taste sweeter than those that are peeled. Yukon Golds, or other yellow-fleshed potatoes, make the creamiest and most luxurious puree. The skins peel off easily after cooking, and the potatoes can hold plenty of butter, growing richer as it is stirred in.
Like most restaurant chefs, Robert uses a tamis, a drum-shaped sieve, to achieve the silkiest puree. Peeled potatoes are set on top of the mesh and pressed through the screen with a plastic scraper. Passing the potatoes through a food mill or a ricer (see Page E2) leaves you with a slightly less homogenous puree but saves the trouble of peeling, and adds a little texture. Robert whips his potatoes in an electric mixer. At home use a tight whisk or a sturdy wooden spoon; a rice paddle will also do the job.
For a slight variation on the classic mash, beat a couple of egg yolks into the crushed potatoes, layer them in a buttered baking dish with the savory olive paste called tapenade. Then sprinkle with grated Parmesan or fontina and bake for a few minutes, just until the mixture puffs up in the pan and the top turns golden.
As comforting as mashed potatoes can be - and they're fine to soak up turkey gravy - sometimes it's nice to have a little crunch with the meal: Crackly skinned roasted potatoes to the rescue.
A good roasted potato is crisp on the outside and fluffy within. A new potato right out of the ground is moist enough to roast nicely, but older potatoes need to simmer until almost soft enough to eat. They're then sent to a hot oven to puff up and firm their skins.
Michael Leviton, chef and owner of Lumiere restaurant in West Newton, prefers to roast creamy, yellow-fleshed potatoes. "I like russets for french fries and gratins," he says, "but a yellow variety like German Butterball, or really any fingerling, are better for the roasting pan."
Leviton starts his potatoes in cold water and brings the heat up. When they are knife tender, he lets the potatoes rest in the water for a few minutes, throws in a few handfuls of ice to stop the cooking, then drains them before chilling. "If you drain potatoes hot they will just dehydrate," he says. Chilled potatoes are halved or quartered. "Cool potatoes cut much more smoothly and don't get gunk all over your knife," says the chef.
To crisp the potatoes, he heats a heavy pan in a hot oven. He tosses the potatoes in vegetable oil, roasts them until golden brown, then sprinkles the pan with gremolata, a chopped mixture of garlic, parsley, and lemon rind. "It's just like how I would do it at home," he says, "if I ever had a chance to cook there."
Lumiere, 1293 Washington St., Newton, 617-244-9199, lumiere restaurant.com
Petit Robert Bistro, 468 Commonwealth Ave., 617-375-0699, and 480 Columbus Ave., 617-867-0600, petitrobertbistro.com