Heat olive oil in a large pot over medium heat.
Add the chopped onion and sauté for 3-4 minutes until translucent.
Add the minced garlic and cook for another 1 minute until fragrant.
Pour in the diced tomatoes with their juice, vegetable broth, dried oregano, dried basil, red pepper flakes, salt, and black pepper. Stir to combine.
Add the dried penne pasta to the pot and stir to submerge the pasta in the liquid.
Bring the mixture to a boil, then reduce heat to medium-low and simmer uncovered for 12-15 minutes, stirring occasionally, until the pasta is cooked and most of the liquid is absorbed.
Stir in the drained tuna gently until evenly distributed and heated through, about 2 minutes.
Remove the pot from heat and sprinkle grated Parmesan cheese and chopped fresh parsley on top.
Serve immediately, garnished with extra Parmesan and parsley if desired.