Preheat oven to 400 degrees.
In a food processor, process tomatoes until smooth. Set aside.
Set up a breading station. One shallow bowl with flour (seasoned with salt & pepper). Another bowl with the eggs, beaten. And a third bowl with the panko breadcrumbs and Parmesan cheese.
Working with a couple slices of pork at a time, dredge in the flour, then the egg, and then the breadcrumbs. Place on a greased baking sheet.
Bake for 15 minutes.
Meanwhile in a large skillet heat olive oil over medium heat. Add onions, and garlic; saute for a few minutes until soft. Add the canned tomatoes, oregano, salt and pepper. Simmer for 5-7 minutes.
Remove the pork from the oven, and place in the tomato sauce. Cover the medallions with cheese.
Place back in the oven for a few minutes, until the cheese is melted and golden brown.