The secret of delectable fries lies in the frying process. The oil needs to be just the right temperature -- too cool, the potatoes will absorb the oil; too hot, the outsides of the potatoes will burn.
Source: Martha Stewart Living Television
4 medium Idaho or russet potatoes
Vegetable or olive oil, for frying
Coarse salt, to taste
Peel potatoes, and cut into desired size and shape. To make thick French fries, slice potatoes lengthwise into 1/4-inch slices, and cut again into 1/4-inch strips. For shoestring potatoes, use a mandoline fitted with the fine julienne blade. Make basket-weave-style fries by fitting the mandoline with the fluted cutting blade; rotate the potato 90 degrees between each pass over the blade. Place sliced potatoes in a large nonreactive bowl, and cover with water.
Drain potatoes, and dry thoroughly with a towel. Heat 3 to 4 inches oil in a heavy-bottomed pot over medium heat. Use a thermometer to ensure the temperature is correct: 325 degrees for French fries, 375 degrees for shoestring and basket-weave fries.
Carefully add potatoes to oil in small batches so as not to lower the temperature of the oil. Cook shoestring and basket-weave potatoes for 2 to 3 minutes, turning occasionally. French fries need to cook for 5 to 6 minutes, turning occasionally. They will not take on much color at this point.
Transfer to a flattened brown paper bag that has been lined with paper towels, and let cool for a few minutes or until just before ready to serve. French fries need to be fried a second time: Raise oil temperature to 375 degrees. and fry for until crisp and golden, about 1 to 2 minutes. Remove from oil, and drain again on the paper bag. Sprinkle with salt, and serve.