In a 12-inch deep sauté pan, drizzle 1 Tablespoon olive or avocado oil and heat to medium. Slice the fresh tomato into very thin slices, about ¼ inch thick and add to the oil.
Mince 4 garlic and add to the tomatoes. Let cook about 7-8 minutes, until tomatoes start to break down and caramelize a bit.
Add one additional Tablespoon oil. Add both 15 ounce cans diced tomatoes with their juices.
Add 8 ounces pasta, ¼ cup Parmesan cheese, 1 teaspoon salt, 1 ½ teaspoon red pepper flakes and ½ teaspoon black pepper. Stir all ingredients until well distributed and so that pasta gets well coated with tomatoes.
Add one cup water, stir once more. Cover and reduce heat to low and cook about 15 minutes, until pasta is al dente, stirring occasionally to prevent pasta from sticking to pan.
Once the pasta is to your liking, take the pan off the heat.
Drain the tuna and set aside.
Dish up pasta mixture into individual serving bowls. Divide the tuna among the bowls, nesting on top or mixing into the hot pasta.
Divide the olives, capers and feta among each portion, sprinkling with additional Parmesan and red pepper flakes, if desired.
Leftovers may be served up to one day later.