This gourmet fetish may have been the progenitor of the twice-baked potato. Remember the wizened bulbs of tin foil? The blobs of orange cheese and bacon bits? A generation of chefs did. In a seminal act of culinary revisionism, they rewrote the recipes. Processed cheese became chevre; bacon bits became pancetta. They introduced the potato to creme fraiche, caviar and truffles. The potato became a star!

By last year, Christopher Holmes, who farms organic potatoes in Maine, had established a Potato of the Month Club. Rather than novelty potatoes, like the precious little blue and yellow varieties, Holmes markets "old-fashioned potatoes" to "people who understand the subtle nuance in common-looking potatoes."

And like some latter-day Parmentier, Marshall took potatoes as her personal mission, cooking them in soups and stews, in bread and dumplings, in gratins and pancakes. She even made a chocolate potato cake. "Lets face it, I lived potatoes," she says. "I love potatoes. I now understand potatoes."

Marshall found two basic types of potatoes. There are potatoes with a high starch content that bake up fluffy and are described as "floury"; and potatoes with a lower starch content with a "waxy" texture that are better for boiling. A potato's species determines its cooking qualities, but grocers think of potatoes in terms of geography. "Maine?" says Marshall, who was born in France. "Idaho? These are places. Places are not potatoes."

High-starch potatoes include the Russet Burbank, which is frequently called "Idaho" but is also grown in other states, and the Russet Arcadia, which is grown in Maine and other states. These potatoes are best for baking, frying, mashing and using in soups. "Eastern potatoes" are medium-starch potatoes, good for pancakes, pan frying, roasting and scalloping. Yukon Golds are also medium-starch, all-purpose potatoes. The White Rose and other red-skinned varieties are low in starch, best for roasting, steaming or using in salads.

To determine whether a potato is floury or waxy, Harold McGee suggests a simple test in his book "On Food and Cooking": Make a solution that is one part salt to two parts water. If the potato is waxy it will float; if it is floury, it will sink.

Marshall's test is more tactile. "When a potato has a thick skin and an oval shape, it is a baking potato," she says. "When it is large and round and has a thin skin, it is an all-purpose potato. When it is baby size, it's steaming time." POTATO PIE WITH RED AND YELLOW PEPPERS (ALL RECIPES ADAPTED FROM "A PASSION FOR POTATOES" BY LYDIE MARSHALL, HARPERCOLLINS) 1 tablespoon unsalted butter 8 phyllo pastry leaves 1/4 cup olive oil, plus 1/4 cup for brushing the pastry leaves 2 pounds russet potatoes, peeled and sliced paper thin 1 large red onion, peeled and sliced paper thin 3/4 cup lightly packed whole basil leaves, finely chopped 1 teaspoon salt 1 teaspoon freshly ground pepper 1 large red bell pepper, roasted, peeled, seeded, deveined and cut into 1-inch strips 1 large yellow bell pepper, roasted, peeled, seeded, deveined and cut into 1-inch strips.