Hushpuppies

Name: Hushpuppies
Ingredients: ¾ cup all-purpose flour; ¾ cup fine-grind cornmeal; 2 teaspoons sugar; 1½ teaspoons baking powder; 1½ teaspoons kosher salt; ½ teaspoon garlic powder; ¼ teaspoon onion powder; ¼ teaspoon freshly ground black pepper; 4 tablespoons chilled unsalted butter, cut into pieces; 1 large egg, beaten to blend; 1 cup buttermilk; ½ small onion, finely chopped; 1 jalapeño, seeded if desired, finely chopped; Vegetable oil (for frying; about 6 cups); Buxton Hall Tartar Sauce (for serving); A deep-fry thermometer