|>>|| No. 12810
When you say you just cook some tomatoes for a bit, is that literally what you mean, or are you adding other stuff in there?
If the former, what the fuck lad, put some onions and garlic in it at least. If you just missed that part out, as said, reducing your sauce is the standard and best way to add depth of flavour.
It's also a very good idea to start your sauce with a mirepoix. Actually I suppose for an Italian sauce it's more apt to call it a soffrito, but anyway, VERY FINELY dice equal parts carrot, onion, and celery, and slowly, very slowly, sweat them in oil, for maybe twenty minutes. You want them to be soft but not browned. Once you've done that dump your tomato in and cook as you usually do. Parsley is a good idea too but add that within the last ten minutes or so of the whole process to keep the fresh flavour in there. Tomato paste can help too but I've never found it particularly necessary. At least one Italian grandmother I know swears by adding a coupe of teaspoons of vegetable bouillon but I think that makes it taste a bit too much like a jar sauce.