Marinate the Mozzarella: In a medium bowl, gently combine the mozzarella cubes, 1 tablespoon (15 ml / 0.5 fl oz) of olive oil, mixed fresh herbs, red pepper flakes, and vinegar.
Season with a pinch of kosher salt and black pepper.
Set aside to marinate at room temperature for at least 30 minutes to allow the flavors to meld.
Sauté the Vegetables: Heat the remaining 2 tablespoons (30 ml / 1 fl oz) of olive oil in a large skillet or Dutch oven over medium-high heat.
Add the chopped garlic and cook for about 30 seconds until fragrant.
Add the sliced onions and bell peppers, and cook, stirring occasionally, until softened and the onions are translucent, about 5-7 minutes.
Simmer the Sauce: Pour the tomato sauce into the skillet with the vegetables.
Stir to combine, reduce the heat to low, and let it simmer gently while you finish the dish.
Season to taste with additional salt and pepper if needed.
Combine and Finish: Transfer the hot, cooked ziti directly to the skillet with the sauce.
Remove the skillet from the heat.
Add the entire bowl of marinated mozzarella (including any liquid), the butter, and the grated Parmesan cheese.
Toss gently but thoroughly until the butter is melted and the cheese is just beginning to get gooey and stringy.
Serve immediately.
Don't discard your pasta water! A splash can be added to the sauce if it seems too thick, helping it cling beautifully to the ziti.
