For the churros, bring the water, butter and salt to a boil, stirring constantly. Add the flour all at once and stir well with a wooden spoon. Stir until the mixture can be separated from the pot. Transfer the batter to a bowl and let cool slightly.
Add the eggs a little at a time with a hand mixer, mixing until the dough is very shiny. Put vegetable oil in a saucepan and heat – the right temperature is reached when you stick a toothpick in it and bubbles form on it.
Now put the dough in a sugargun with a large star nozzle or in a piping bag with this attachment, and pipe strands about 5cm long in order.
After about 5 minutes, place the churros on paper towels to drain. Sprinkle with powdered sugar.