For the sauce, heat the olive oil in a dutch oven or large sauce pot over medium heat. Add in onions and garlic and cook until onions are translucent & garlic is fragrant. Next, add in tomato pasta and cook for about 30 seconds until it becomes a rusty red color. Finally, deglaze bottom of the pan with the balsamic. Add in remaining sauce ingredients and stir until combined thoroughly. Bring the sauce to boil and then allow to simmer on low heat for at least 30 minutes. Once the sauce is cooked, use an immersion blender or transfer to a regular blender to blend and smooth the sauce out.
*I recommend making the meatballs a few hours beforehand so they can set up in the fridge - it helps them hold their shape better and for the flavors to meld.