Pat tenders dry; add salt and pepper. Put flour in shallow dish, egg beaten with egg-wash water in another, and cornmeal mixed with Parmesan in a third. Lightly flour, egg-dip, and cornmeal-coat tenders; discard unused mixtures.
Heat 2 tablespoons oil in 12-inch skillet over medium. Cook 6 tenders 3 to 4 minutes per side until golden and 165°F inside; transfer to clean plate. Repeat with 2 more tablespoons oil and remaining 6 tenders.
Carefully wipe dark loose crumbs and excess oil from empty skillet with paper towels held in tongs. Reduce to medium-low; add remaining tablespoon oil and cook garlic 30 seconds.
Add tomatoes, oregano, and sauce water. Simmer 8 to 10 minutes, stirring occasionally, until spoon-coating.
Arrange cooked tenders over sauce with exposed edges, slightly overlapping if needed. Spoon sauce across centers; scatter mozzarella. Cover over low 2 to 3 minutes until cheese melts.
Remove from heat; serve 3 tenders with sauce per portion.