Preheat the oven to 325 degrees F.
Pound out the cutlets until they are 1/8 inch thick and give them a few whacks with the tenderizing side of the mallet. Season the cutlets on both sides with salt and pepper.
Heat the olive oil in a 12-inch nonstick saute pan over medium-high heat until hot. Add the beef in batches and sear on both sides, 2 minutes per side. Remove the first batch from the pan and place in an ovensafe baking dish while you work on the second batch.
Ladle the Red Sauce with Anchovy and Capers over the meat to cover. Then add a few small hand-torn pieces of mozzarella on top of each cutlet. Sprinkle with some chopped parsley. Bake just until the mozzarella is melted, 15 to 20 minutes.
In a blender or food processor, puree the tomatoes to a smooth, creamy consistency.
Add the olive oil to a large pan over medium heat. Once hot, add the anchovies and onions and saute until the onions are soft and the anchovies have melted into the onions. Toss in the capers and garlic, and if you'd like to make the sauce spicier, add a pinch of red pepper flakes. Saute until the garlic is fragrant.
Add the tomatoes and season with salt and pepper. Bring to a simmer and simmer on a medium-low flame for about 30 minutes. Strive for balance in the consistency of the sauce; it has to be fluid but it should not look overly wet. A few minutes before taking the sauce off the fire, add half the basil and more salt and pepper if needed. Garnish with the remaining basil just before serving.