Yes to what BrownParent says. An authentic Italian fresh tomato sauce does not cook the tomatoes, just heats them. I would use a lot less of the onion, maybe 1/4, compared to the recipe.
I ate like this a lot during my single years, adding just about any vegetable imaginable. If you eat out of the pot, one less dish to wash.
With extra zucchini, we shred them in the Cuisinart with carrots and beets for a quick raw veggie salad.