Prepare your base. Heat olive oil in a large Dutch oven or deep skillet over medium heat. Add onions, carrots, and celery, cooking for 5-7 minutes until softened but not browned.
Add aromatics. Stir in minced garlic and cook for 30 seconds until fragrant, being careful not to burn it as this can create bitterness.
Brown the meat. Add ground beef to the vegetable mixture, breaking it apart with a wooden spoon. Cook until no longer pink, about 5-6 minutes.
Enhance with tomato paste. Add tomato paste and stir continuously for 2 minutes, allowing it to caramelize slightly which deepens the overall flavor of your sauce.
Deglaze the pan. Pour in the red wine (or broth), scraping up any browned bits from the bottom of the pan. Let it simmer until reduced by half, about 3-4 minutes.
Add lentils and liquids. Stir in the rinsed lentils, crushed tomatoes, and broth. Add bay leaves, dried herbs, red pepper flakes, salt, and pepper.
Simmer properly. Bring the mixture to a boil, then reduce heat to maintain a gentle simmer. Cover partially with a lid and cook for 25-30 minutes, stirring occasionally, until lentils are tender but still hold their shape.
Finish with acid. Remove bay leaves and stir in balsamic vinegar. Taste and adjust seasonings as needed.
Rest before serving. Allow the sauce to sit for 5-10 minutes before serving – this short rest helps flavors meld together.
Serve with pasta. Toss with your favorite cooked pasta, garnish with fresh herbs and a generous sprinkle of Parmesan cheese.