In a 3 to 4-quart pan combine water, salt, granulated sugar and butter over low heat; cook, stirring until butter is melted. Increase heat to high and bring mixture to a rollingboil. Add flour all at once and remove from heat.
With a spoon, beat until mixture is smooth and thick and pulls away from side of pan. Add eggs one at a time, beating well after each addition, until dough is smooth and shiny. Stir in lemon extract and let cool.
Pour oil to a depth of 1 1/2 inches into a wide frying pan and heat to 375 degrees on a deep frying thermometer.
Meanwhile, spoon half the dough into a large pastry bag or cookie press fitted with a large star tip. Squeeze a 7 to 9-inch ribbon of dough into hot oil; slice off. Cook 2 or 3 ribbons at a time until well browned (about 5 minutes).
Remove churros and drain on paper towels. While warm, sprinkle churros liberally with powdered sugar. Serve immediately. Makes 1 1/2 dozen churros.