In a small saucepan over medium heat, combine the water, sugar, salt, and vegetable oil.
Bring the mixture to a boil.
Remove from the heat and stir in the flour until the dough comes together and forms a ball.
Heat the frying oil in a deep fryer or heavy-bottomed pot to 375°F (190°C).
Transfer the dough to a piping bag fitted with a star tip.
Pipe 4- to 6-inch strips of dough carefully into the hot oil.
Fry the Homemade Churros until golden brown, about 2 minutes per side.
Remove them with a slotted spoon and drain on paper towels.
In a shallow bowl, mix the sugar and cinnamon.
Roll the warm churros in the cinnamon-sugar mixture until evenly coated.
Serve immediately, with chocolate sauce if desired.