Heat olive oil in a large saucepan over medium heat.
Add chopped onion and sauté until translucent.
Stir in minced garlic and cook for an additional minute.
Add the crushed tomatoes to the saucepan.
Sprinkle in dried oregano and sugar to balance acidity.
Season with salt and pepper to taste.
Bring the mixture to a simmer, then reduce the heat.
Let the sauce simmer for 20 minutes, stirring occasionally.
Adjust seasonings as needed, adding red pepper flakes if desired.
Remove from heat and serve garnished with fresh basil and Parmesan cheese.