Separate 1/3 of the chopped onion and garlic to be used for the sauce.
Add a drizzle of olive oil to a sauté pan and then add in the rest of the chopped garlic and onion. Sauté until golden and then set aside on a dish to cool off.
Meanwhile, to prepare the tomatoes, cut off a thin slice off of the top and then use a knife to cut out the inside of the tomatoes, making sure not to cut into the bottom. Use a spoon to get rid of all of the seeds and flesh from the inside of the tomato.
Do not discard the tomato flesh. Remove the chunky pieces and chop them up into smaller pieces to make a sauce. Discard the water and seeds. Place the chopped tomato pulp into a strainer to further remove excess water.
Preheat oven to 400°F and place rack in middle position.
Sprinkle salt and black pepper into each tomato and then flip each tomato upside down to drain more water out from the inside of the tomatoes.
Meanwhile, in a large mixing bowl, add the ground pork, the sautéed garlic and onion, egg, cheese, panko breadcrumbs, salt and black pepper. Mix until fully combined.
Lightly oil the bottom of a baking dish. Stuff each tomato with the pork stuffing until filled to the top and then place the thin tomato slice on top. Place on the baking dish and then cook in the oven for forty minutes.
Meanwhile, add a drizzle of olive oil to a sauté pan. Add in the separated garlic and onion. Sauté until golden and then add in the strained tomato pulp. Sauté over a very low flame until the stuffed tomatoes are done cooking.
After forty minutes, remove the stuffed tomatoes from the oven. Place the simmered tomato sauce in a bowl. Scoop a stuffed tomato out of the baking dish and place on a dish. Add as much of the tomato sauce that you'd like on top and serve.