Yes, onion is generally considered a good addition to spaghetti.
Onions contribute a savory and aromatic flavor base that enhances the overall taste of the spaghetti sauce. When cooked properly, onions soften and release their sweetness, complementing the acidity of tomatoes and other sauce ingredients. The reference provided suggests that the secret lies in cooking the onions slowly to avoid browning and instead achieve a hint of color, maximizing their flavor contribution. When combined with cheese, herbs, and butter, the result is an "amazingly tasty" dish.
The appropriateness of onion in spaghetti ultimately depends on personal preference, but it is a common and widely accepted ingredient. Some recipes may call for specific types of onions (e.g., yellow, white, or red) to achieve different flavor profiles.
