Step 1: In a small bowl, combine warm water, sugar, and yeast. Let it sit for 5-10 minutes until it becomes foamy.
Step 2: In a large mixing bowl, whisk together the all-purpose flour, glutinous rice flour, and salt. Pour in the yeast mixture and stir until a thick, sticky dough forms.
Step 3: Cover the bowl with plastic wrap and let it rise in a warm, draft-free area for 45-60 minutes, or until doubled in size.
Step 4: Skewer the half-hot dogs and mozzarella blocks onto wooden chopsticks or thick skewers, placing the hot dog on the bottom and the cheese on top. Keep them in the refrigerator until ready to dip.
Step 5: Transfer the risen dough into a tall, narrow glass. Dip each skewer into the dough, swirling to ensure it is completely encased.
Step 6: Immediately roll the dough-covered skewer in panko breadcrumbs, pressing firmly so the crumbs adhere to all sides.
Step 7: Heat 2-3 inches of oil in a deep pan to 350°F (175°C). Fry the corn dogs in small batches for 3-5 minutes until golden brown and crispy.
Step 8: Remove from oil and drain briefly on a wire rack. While still hot, roll in granulated sugar and drizzle with ketchup and mustard.