2 c water 1 package active dry yeast
1 medium-sized boiling potato, 1 tsp plus 2½ c sugar
peeled and quartered 6 to 6½ c unsifted flour
4 T butter, cut into ½-inch bits 1 tsp salt
and softened, plus 2 tsp butter, 2 eggs
softened Vegetable oil for deep frying
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In a small heavy saucepan, bring the water to a boil over high heat. Drop
in the potato quarters and boil briskly, uncovered, until a quarter can be
easily mashed against the side of the pan with the back of a fork.Drain the potatoes in a sieve set over a bowl, pat them dry with a kitchen towel and return them to the pan. (Measure and reserve 1½ cups of the potato water.) Then mash the potatoes to a smooth purée with the back of a fork (you will need about ½ cup of the potato purée). Beat the 4 tablespoons of butter bits into the potatoes, and cover the pan to keep the purée warm.
When the reserved potato water has cooled to lukewarm (110° to 115°), pour ¼ cup of it into a shallow bowl. Add the yeast and 1 teaspoon of sugar. Let the mixture stand for 2 or 3 minutes, then stir well. Set the bowl in a warm, draft-free place, such as an unlighted oven, for about 5 minutes, or until the yeast bubbles up and the mixture almost doubles in volume.
Combine 6 cups of the flour, ½ cup of the sugar and the salt in a deep mixing bowl, and make a well in the center. Drop in the potato purée, the yeast mixture, the eggs and the remaining 1¼ cups of potato water. With a large wooden spoon, mix the ingredients together and stir until the dough is smooth and can be gathered into a soft ball.
Place the ball on a lightly floured surface and knead, pushing the dough down with the heels of your hands, pressing it forward and folding it back on itself.
As you knead, sprinkle flour over the ball by the tablespoonful, adding up to ½ cup more flour if necessary to make a firm dough. Then continue to knead for about 10 minutes longer, or until the dough is smooth, shiny and elastic.
With a pastry brush, spread the 2 teaspoons of softened butter evenly over the inside of a large bowl. Set the dough in the bowl and turn it about to butter the entire surface. Drape the bowl with a kitchen towel and put it in the draft-free place for about 1½ hours, or until the dough doubles in bulk.
Line one or two large baking sheets with wax paper. Place the dough on a lightly floured surface and roll it out into a rough rectangle about ½-inch thick. With a small, sharp knife or a pastry wheel, cut the dough into 2-inch squares, and make a 1-inch slash in the center of each. Arrange the squares about 1 inch apart on the paper-lined baking sheet and return them to the draft-free place to rise for 30 to 45 minutes, or until doubled in bulk.
Pour vegetable oil into a deep fryer or large heavy saucepan to a depth of 3 inches and heat it to a temperature of 375° on a deep-frying thermometer. At the same time, place about ½ cup of the remaining sugar in a paper bag and set it aside.
Deep-fry the dough squares 4 or 5 at a time, turning them with a slotted spoon, for 3 minutes, or until they are puffed and brown. Drain the fastnachts, or doughnuts, briefly on paper towels, then drop two at a time into the bag and shake to coat them with sugar. (Add more sugar to the bag as needed.) Place the fastnachts on a plastter to cool while you fry and sugar the rest. Makes about 2 dozen doughnuts.
