Step 1: Heat the olive oil in a large, heavy-bottomed pot or Dutch oven over medium heat.
Step 2: Add the diced onion and cook, stirring occasionally, until softened and translucent, about 5-7 minutes. Do not let it brown.
Step 3: Add the minced garlic and cook for another 1-2 minutes until fragrant, being careful not to burn it.
Step 4: If using ground meat, add it to the pot and break it up with a spoon. Cook until browned, then drain any excess fat.
Step 5: Pour in the crushed tomatoes and diced tomatoes, along with the tomato paste. Stir well to combine all ingredients.
Step 6: Add the dried oregano, dried basil, red pepper flakes (if using), and bay leaf. Season generously with salt and black pepper.
Step 7: Stir in the sugar. This helps to balance the acidity of the tomatoes.
Step 8: If the sauce seems too thick, add about 1/2 cup of water or vegetable/beef broth to achieve a looser consistency.
Step 9: Bring the sauce to a gentle simmer. Once simmering, reduce the heat to low, cover the pot partially, and let it simmer for at least 1.5 to 2 hours, or up to 3 hours for deeper flavor. Stir occasionally to prevent sticking.
Step 10: About 15 minutes before serving, stir in the fresh basil and fresh parsley.
Step 11: Remove the bay leaf before serving.
Step 12: Serve hot over your favorite pasta, garnished with freshly grated Parmesan cheese and an extra sprinkle of fresh basil.