In a medium saucepan, combine water, butter, and salt. Bring to a boil.
Reduce heat to low and add the flour, stirring constantly until a dough forms.
Remove from heat and let cool for 5 minutes.
Beat in eggs, one at a time, until the mixture is smooth and glossy.
Heat oil in a deep pan to 375°F (190°C).
Transfer dough to a piping bag with a star tip and pipe 1-inch pieces directly into the hot oil.
Fry until golden brown, then remove and drain on paper towels.
Mix sugar and cinnamon in a bowl and toss warm churro bites until coated.