Prepare Dough: In a medium saucepan, combine the water, unsalted butter, 1 tablespoon of granulated sugar, and salt. Bring to a boil over medium heat. Remove from heat and add the flour all at once, stirring vigorously until the mixture forms a ball and pulls away from the sides of the pan.
Cool and Add Eggs: Allow the dough to cool for 5 minutes. Transfer the dough to a mixing bowl. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract until the mixture is smooth and glossy.
Heat Oil: In a deep skillet or large pot, heat about 2 inches of vegetable oil to 375°F (190°C).
Pipe Dough: Transfer the dough to a piping bag fitted with a large star tip. Pipe 1-inch pieces of dough into the hot oil, using scissors or a knife to cut the dough from the tip.
Fry Churro Bites: Fry the churro bites in batches, turning occasionally, until they are golden brown and cooked through, about 2-3 minutes per batch. Use a slotted spoon to transfer the churro bites to a paper towel-lined plate to drain.
Coat Churro Bites: In a shallow bowl, mix together the 1/2 cup of granulated sugar, ground cinnamon, and sea salt. While the churro bites are still warm, roll them in the cinnamon-sugar mixture to coat evenly.
Serve: Serve the sweet and salty churro bites warm. They are delicious on their own or can be paired with dipping sauces like chocolate or caramel for extra indulgence.