In a large bowl, whisk together the flour, cornmeal, sugar, baking powder, and salt. In a medium bowl, whisk the egg, buttermilk, and 1 Tbsp. oil. Add the egg mixture to the dry ingredients and stir until a thick batter forms. Let it sit until hydrated, about 5 minutes.

Meanwhile, pour oil into a large, heavy pot to a depth of 2 inches. Heat over medium-high heat until a deep-fry or instant-read thermometer registers 350°F.

Pour the batter into a tall glass, if desired. Insert a skewer through a sausage and dip it into the batter, coating it completely. Holding the skewer, carefully lower the sausage into the hot oil.

Fry, turning occasionally, until golden brown, about 2 to 3 minutes. Transfer to a wire rack set in a baking sheet to drain.

Arrange the mini corn dogs on a platter. Serve warm with mustard and/or ketchup alongside.