In a large skillet over medium heat, add the olive oil.
Sauté the diced onion, carrot, and celery until softened and fragrant, about 5 minutes.
Add the ground beef to the skillet, breaking it up with a wooden spoon, and cook until browned.
Stir in the minced garlic and cook for 1 minute until aromatic.
Pour in the tomato puree and add the dried oregano, sea salt, and black pepper.
Lower the heat and simmer the sauce for 15 minutes to allow the flavors to meld.
While the sauce simmers, cook the tagliatelle in boiling salted water until al dente, then drain.
Toss the cooked tagliatelle with the Bolognese sauce until well coated.
Serve immediately, garnished with grated Parmesan cheese.