Fill a Dutch oven or other heavy pot with the canola oil, and heat to 350 degrees F. Line a plate with paper towels.
In a large bowl, whisk together the cornmeal, flour, sugar, baking powder and 1/4 teaspoon salt. Add the eggs and buttermilk, and stir to combine.
Working in batches, dip each hot dog in the batter to coat, let the excess drip off, and then fry until golden, 3 to 5 minutes. With a slotted spoon, transfer the corn dogs to the paper-towel-lined plate to drain.
Serve with mustard.
Add the mustard powder, honey, vinegar, mustard seeds and 1/3 cup water to a mixing bowl. Stir to combine. Transfer to an airtight container and refrigerate for up to a month.