• 4 pounds large all-purpose potatoes
• 2 to 3 cups water-rendered goose or duck fat or olive oil
• 6 tablespoons unsalted butter
• 1 bunch flat-leaf parsley, stemmed, leaves coarsely chopped
• coarse sea salt

Peel the potatoes and trim each one into a neat rectangle about 3 inches long. Cut each potato lengthwise into ½-inch-thick slices, then cut each slice into ½-inch strips.

Melt 2 to 3 inches of fat in a large, deep, heavy skillet over medium heat until very hot, 375°F on a deep-frying thermometer.

Thoroughly pat the potatoes dry. Fry them in batches, turning the strips occasionally, until golden brown, 5 to 10 minutes. Drain on paper towels and sprinkle with salt.

When all the potatoes are cooked, pour off the fat and wipe out the skillet. Melt the butter in the same pan. Add the potatoes and heat through, tossing frequently. Add the parsley, season with coarse salt, and serve.