Heat the olive oil in a large pot over medium heat until it is warm and ready for cooking.
Add the diced onion and cook while stirring occasionally until it softens and becomes translucent.
Stir in the minced garlic and cook briefly, making sure to stir gently so it does not burn.
Pour in the crushed tomatoes and mix well so the base of the sauce is evenly combined.
Add the dried oregano, basil, salt, pepper, and sugar if using, then stir to distribute the seasonings evenly.
Bring the sauce to a gentle simmer, allowing the flavors to begin developing.
Reduce the heat and let the sauce simmer slowly, stirring occasionally to prevent sticking and to help the flavors deepen.
If the sauce becomes too thick, add a small amount of water gradually until the desired consistency is reached.
Taste the sauce and adjust the seasoning as needed before serving.
Serve over freshly cooked spaghetti or use as desired.