Pre-heat the oven to 425 degrees. Slice the top off of the tomatoes, then use a spoon to hollow them out completely.
Place the tomatoes in a cast iron skillet or baking dish, then drizzle with olive oil.
In a large bowl, combine the lentils, mozzarella, breadcrumbs, dried oregano and fresh basil. Toss and season to taste.
Spoon the mixture into the tomatoes then place the top back on each tomato.
Bake for 25 minutes or until tomatoes are soft and cooked through.