In a large bowl, combine flour, sugar, baking soda, baking powder, and salt; mix well.
In a medium bowl, beat eggs, milk, and vanilla until well blended. Add to flour mixture and beat until smooth.
In a medium saucepan, heat 1-inch of oil over medium-high heat until hot, but not smoking. Holding a finger over bottom of a funnel with a 5/8" opening, pour 1/2 cup of batter into funnel.
Drizzle batter into hot oil, swirling it in circles from center outward. Fry until golden, turning once. Drain on paper towels and sprinkle with confectioners' sugar; serve warm.