2 cups plus 2 tablespoons all-purpose flour, plus more for dusting
1 tablespoon baking powder
1 cup water
1 cup sparkling water
1 teaspoon vanilla extract
3 tablespoons unsalted butter
Pinch of kosher salt
2 large eggs
2⁄3 cup sugar
2 teaspoons ground canela or cinnamon
Vegetable oil for deep frying

Combine the flour and baking powder in a bowl.

Combine the water, sparkling water, vanilla, butter, and salt in a medium saucepan and bring to a boil; once the butter has melted, turn off the heat. Add the flour mixture all at once, whisking vigorously to prevent lumps. Change to a wooden spoon or silicone spatula and stir vigorously, in one direction, until the mixture is uniform and smooth, with no lumps, about a minute.

Immediately scrape the mixture into the bowl of a stand mixer fitted with the paddle attachment. Beat on low speed until you no longer see any steam rising and the dough has cooled to lukewarm, about 2 minutes. (This helps make a uniform dough that is not too stiff and is cool enough to add the eggs without cooking them.)

One by one, beat in the eggs, making sure the first one is incorporated before adding the second one. Scrape down the bowl and beat until the dough is smooth. Scrape down the bowl again, then beat at high speed for another minute, or until the dough is soft, smooth, and malleable. It should resemble Play-Doh. Scrape down the bowl and beater, remove the bowl from the mixer, cover with a clean kitchen towel or with plastic, and let the dough rest for at least 20 minutes. The rest will help the gluten in the flour relax so that the dough will be easier to work with and the churros won’t crack.

Meanwhile, combine the sugar and canela or cinnamon in a bowl and spread on a large plate. Place a cooling rack on a baking sheet lined with paper towels. Line another baking sheet with parchment and very lightly dust it with flour.

In a Dutch oven or deep heavy skillet, heat about 2 inches of vegetable oil to 350 to 375 degrees F. You can test the oil with a teaspoon of dough; the oil is ready when it bubbles energetically around the dough.

Transfer all or some of the churro dough to a pastry bag fitted with a large (½ – to ¾ -inch) open star tip, or use a churro press, if you have one. Pipe the dough into 6- to 8-inch-long strips on the parchment-lined baking sheet. You can begin frying the churros as soon as you have piped out 5 or 6. Working in batches, carefully place the shaped churros in the hot oil, taking care not to crowd the pot.

They should float to the top almost immediately. Fry for 4 to 6 minutes, or until golden and crisp, turning as soon as one side is golden brown, about halfway through. The churros may resist being turned, but use tongs and be persistent to make sure they are evenly browned. Then use the tongs or a slotted spoon to remove them and let cool for a few seconds on the cooling rack. While they are still hot, toss them in the cinnamon sugar to coat. Serve hot or warm.

Cook’s Note ► You can serve the churros with cajeta or dulce de leche, chocolate syrup, Nutella, jam, or honey, if you like.