For the coating whisk together 1/2 cup sugar and cinnamon in a shallow dish, set aside.
In a small saucepan over medium heat, combine water, sugar, salt, and butter. Bring to a boil and remove from heat.
Stir in flour and beat until mixture forms a ball. Keep beating vigorously to cool the mixture.
Add in the vanilla and the eggs one at a time while keep beating the mixture. the dough will look as if it is falling apart, but it quickly returns to its optimal state.
Transfer to a piping bag fitted with a rounded star tip (no bigger than 1/2-inch).
Heat oil in a wide pot until it reaches a temperature of 170°C/340°F.
Carefully pipe mixture into preheated oil, into about 6-inch lengths, cut end with clean scissors.
Let fry until golden brown, about 2 minutes per side. Transfer to paper towels to dry briefly then transfer to cinnamon sugar mixture and roll to coat.
Repeat process with remaining dough (frying no more than 5 at once). Serve warm.