Step 1: In a medium saucepan, combine water, butter, 2 tablespoons granulated sugar, and salt. Bring the mixture to a rolling boil over medium-high heat, stirring occasionally to ensure the butter melts and the sugar dissolves completely.
Step 2: Once boiling, remove the saucepan from the heat. Add all the all-purpose flour at once. Stir vigorously with a wooden spoon or sturdy spatula until the mixture comes together and forms a smooth ball of dough that pulls away from the sides of the pan.
Step 3: Return the saucepan to low heat and continue to cook the dough, stirring constantly, for about 1-2 minutes. This helps to dry out the dough, essential for a crispy churro. You should see a thin film form at the bottom of the pan. Transfer the dough to a large mixing bowl.
Step 4: Allow the dough to cool for about 5-10 minutes. It should still be warm but cool enough to safely handle.
Step 5: Add the eggs one at a time, mixing thoroughly after each addition until fully incorporated. The dough may look separated and lumpy at first, but keep mixing until it becomes a smooth, thick, and shiny paste.
Step 6: Heat about 2-3 inches of vegetable oil in a deep, heavy-bottomed pot or Dutch oven to 350-375°F (175-190°C). Use a candy thermometer to monitor the temperature.
Step 7: While the oil heats, prepare your piping bag. Fit a large star tip (like Wilton 1M or 21) into a piping bag. Spoon the churro dough into the bag. Prepare the cinnamon sugar mixture in a shallow dish by combining 1/2 cup granulated sugar and 1 teaspoon ground cinnamon.
Step 8: Carefully pipe 4-6 inch strips of dough directly into the hot oil, using kitchen shears or a knife to cut the dough cleanly from the tip. Do not overcrowd the pot; fry 3-4 churros at a time.
Step 9: Fry for 2-4 minutes, or until golden brown and cooked through, turning them occasionally to ensure even browning.
Step 10: Using a slotted spoon or spider skimmer, remove the fried churros from the oil and immediately transfer them to a plate lined with paper towels or a wire rack to drain any excess oil.
Step 11: While still warm, roll the churros generously in the cinnamon sugar mixture. Serve immediately with your favorite dipping sauce, such as chocolate or dulce de leche.