Prepare the Bread Base - Remove the crusts from each slice of bread using a knife. Place the crustless bread slices on a flat surface and flatten them completely with a rolling pin. This creates a thin, pliable base that will easily roll around the filling without breaking.

Create the Tuna Filling - In a medium bowl, combine the drained tuna, salt, black pepper, chopped carrots, mayonnaise, pickle relish, and shredded mozzarella cheese. Mix thoroughly until all ingredients are well incorporated and the filling has a consistent texture.

Prepare the Egg Wash - Crack the eggs into a shallow bowl and beat them until fully combined. This egg wash will help seal the bread and create a sticky surface for the breadcrumbs to adhere to.

Assemble the Tuna Pies - Brush the flattened bread slices with the beaten egg on all sides. Place a spoonful of the tuna mixture in the center of each bread slice. Carefully roll up the bread to enclose the filling, then press the edges with a fork to seal.

Coat with Breadcrumbs - Dip each rolled tuna pie into the beaten eggs until evenly coated. Roll them in breadcrumbs, ensuring they're completely covered for maximum crispiness.

Fry to Golden Perfection - Heat oil in a pan over medium heat. Once hot, carefully add the tuna pies and fry until all sides are crispy and golden brown, turning occasionally for even cooking.

Drain and Serve - Remove the fried tuna pies from the oil and place them on paper towels to absorb excess oil. Allow them to cool slightly before serving warm.