Heat olive oil in a large pot over medium heat. Add the diced onion and minced garlic, cooking until fragrant and softened.
Add the ground beef or turkey and cook until browned, breaking it up as it cooks. Drain excess fat if necessary.
Stir in crushed tomatoes, tomato paste, and tomato sauce.
Season with sugar, salt, pepper, basil, oregano, and red pepper flakes (if using).
Reduce heat to low and simmer for 30–45 minutes, stirring occasionally to let the flavors meld.
Taste and adjust seasoning as needed.
