Make the batter. In a large bowl, whisk together the pancake mix, cornmeal, milk and a pinch of salt. (The batter should be a bit tighter than pancake batter.) Let rest 5-10 minutes. If needed, add a bit more milk to loosen.
Dunk and fry. In a large pot or fryer, bring at least 4 inches of oil to 350° F. Dunk hot dogs in the batter and remove with a fork. Gently drop them into the oil and fry, rotating if needed, until golden brown all over, about 4-6 minutes. Remove and serve with mustard.