Arrange three large bowls for breading. Place the flour in the first bowl, the beaten eggs in the second, and the breadcrumbs in the third. Whisk the garlic powder, onion powder, and Italian seasoning into the flour until evenly combined. Line a sheet tray with parchment paper and set a wire rack nearby.

Season both sides of the pounded flank steak cutlets with salt and black pepper. Dredge each piece first in the seasoned flour, then in the beaten egg, and finally in the breadcrumbs, coating each cutlet thoroughly. Transfer the breaded steaks to the wire rack and repeat with the remaining pieces.

In a wide skillet or sauté pan, add enough avocado oil to create approximately 1 inch of depth. Heat the oil over medium heat for about 2 minutes, or until ready for frying.

Working in batches, place the breaded steaks into the hot oil. Fry for approximately 2 minutes per side, or until golden brown and cooked through. Adjust the heat as needed to prevent over-browning. Remove the cooked steaks and place them on the parchment-lined sheet tray. Repeat with the remaining cutlets.

Warm the marinara sauce in a saucepan over medium heat until hot. Transfer the sauce to a large bowl if desired for easier dipping.

Submerge each fried steak cutlet briefly in the hot marinara sauce so that it is fully coated.

Place each sauced steak cutlet onto a soft roll. Top generously with grated mozzarella cheese.

Place the assembled sandwiches under the broiler and heat until the mozzarella is melted, gooey, and lightly browned.

Wrap each sandwich in aluminum foil and let stand for 3 to 5 minutes. This allows the sandwich to steam slightly and the flavors to settle together.

Serve immediately while hot.