"Heh, come over here, kid, learn something. You never know, you might have to cook for 20 guys someday. You see, you start out with a little bit of oil. Then you fry some garlic. Then you throw in some tomatoes, tomato paste, you fry it; ya make sure it doesn't stick. You get it to a boil; you shove in all your sausage and your meatballs; heh…? And a little bit o' wine. An' a little bit o' sugar, and that's my trick."
Everything I know about spaghetti sauce, I learned from Pete Clemenza. Which is to say, not much.
I tried it recently with half a clove of garlic and a diced onion. First I cooked the beef and took it off the pan. Then I added the onions and garlic. Next, a 1/2 cup of red wine reduced to 1/4 cup. I added two spoonfuls of tomato paste and a couple diced roma tomatoes, thyme, cumin, cayenne, and flour for thickening. Plus a pinch of sugar, of course.
Result: not nearly thick enough, very strong winy taste. Tomato paste makes me trepidatious; maybe add more? (serving size I'm shooting for is 2-4).
Here's another food blogger's approach.