Add butter, sugar, water, and salt to a saucepan over medium-high heat.
Bring it to a boil.
Reduce heat to medium and add flour, stirring constantly with a spatula until the mixture is smooth.
Remove from heat and transfer the mixture to a mixing bowl. Let it cool for a few minutes.
Add vanilla and egg. Blend using an electric hand mixer. Beat until smooth.
Transfer the mixture to a large piping bag fitted with a rounded star tip.
Heat about 2-inch vegetable oil in a large pot over medium-high heat to 350 F degrees.
Pipe the mixture into the oil, and cut end with kitchen scissors.
Fry about 4-5 minutes until golden brown. Transfer a plate lined with paper towels.
Coat with cinnamon sugar. Serve and enjoy!