Bring a large pot of salted water to a boil and prepare the pasta according to the package instructions, cooking until al dente. Drain and toss with a drizzle of olive oil to prevent sticking. Set aside.
Heat the olive oil in a large skillet over medium heat. Add the onion and carrot and cook, stirring occasionally, for 5 to 8 minutes, or until softened. Add the mushrooms, garlic, salt, and several grinds of pepper and cook for another 5 to 8 minutes, stirring occasionally, or until the mushrooms are tender.
Stir in the balsamic and tamari, then add the lentils and marinara. Cook, stirring, for 2 minutes, or until the sauce is well-combined and heated through.
Add the pasta to the skillet and toss to combine. Portion onto plates and serve with Parmesan and fresh parsley for garnish.