In a medium saucepan, combine water, sugar, salt, and vegetable oil. Heat over medium-high until it boils, stirring occasionally.

Remove the saucepan from heat and stir in all-purpose flour until a smooth dough forms.

Allow the dough to cool slightly, then add eggs one at a time, mixing well after each addition. Stir in vanilla extract.

Heat vegetable oil in a deep skillet to about 350°F (175°C).

Prepare a plate with paper towels to drain the churros after frying.

Place the dough in a piping bag fitted with a large star tip and pipe lengths of dough into the hot oil, cutting with scissors.

Fry for about 2-3 minutes per side until golden brown, flipping halfway through for even cooking.

Remove churros and drain them on paper towels to absorb excess oil.

Mix sugar and ground cinnamon in a shallow dish.

While churros are warm, roll them in the sugar-cinnamon mixture. Serve with chocolate sauce for dipping, if desired.