Finely dice the onion, carrot, and celery to create a consistent mirepoix base.
Heat the olive oil in a large skillet or heavy-bottomed pot over medium heat.
Add the diced vegetables and sauté for 5-7 minutes until they are soft and translucent.
Add the lean ground beef to the pot, using a wooden spoon to break it into small crumbles as it browns.
Stir in the minced garlic, sea salt, black pepper, and dried oregano, cooking for another minute until the spices are fragrant.
Pour in the tomato puree and water, stirring well to combine all ingredients.
Reduce the heat to low, cover, and simmer the sauce for at least 30 minutes to allow the flavors to meld and the beef to become tender.
While the sauce simmers, bring a pot of salted water to a boil and cook the pappardelle according to package instructions until al dente.
Drain the pasta and add it directly to the beef ragu, tossing gently to ensure the wide noodles are fully coated in the sauce before serving.