Cut the mozzarella. Cut the mozzarella block into ½ inch wide pieces. The length is personal preference, but we prefer around 3 inches.
Prep the breading components. Use three separate bowls. In the first, place the cornstarch or flour, in the second the beaten eggs and milk, and in the last the panko, flour, Italian seasoning, and salt.
Dip. Dip the mozzarella first in the flour or cornstarch, then the liquids, then the flour and breadcrumbs. If necessary, press the cheese sticks into the breadcrumbs to get them to stick. Work in small batches.
Freeze. Place the breaded sticks on a plate or baking sheet and let them chill in the freezer for an hour. This will help the breading stick and keep the cheese firm as they fry.
Fry. Preheat the oil to 375℉, checking the temperature with a candy thermometer. Fry the mozzarella sticks for 2-3 minutes until golden brown.
Serve. Remove to a paper towel and serve immediately with ranch or marinara sauce.