Preheat oven to 450 degrees F. Cut off the top of the head of garlic, with the cloves still connected, but just enough to expose them a bit. Place in some foil and drizzle a little bit of olive oil over the top. Wrap the foil around the garlic, and roasted for 45 minutes in the oven. You can do this ahead of time if you'd like, or while the other ingredients are cooking.
In a pot over medium high heat, heat the olive oil. When oil begins to shimmer, add in the chopped onion and sauté until translucent, about 5 minutes, stirring often. The onions should be golden and shimmering. Add in the red wine vinegar and stir into the onions. Add in the chopped tomatoes and stir everything together. Cover the pot with lid and increase heat to medium high. Steam the tomatoes for 8 minutes - this will soften the tomatoes, help them to break down and allow more flavour to be infused into them. They will not burn since a lot of liquid will be released, but you can still check every few minutes to ensure.
Remove the pot and reduce heat to medium. Add in the salt, pepper, oregano and parsley and stir everything in to combine. Squeeze the roasted garlic cloves into the tomato mixture. It will be butter soft, so you can just squeeze them out of the skins. Stir together again.
Reduce heat to medium low (should be simmering) and place pot cover back on slightly but not to completely cover the pot. Simmer the sauce for 30 minutes up to an hour, if desired. The skins should slip right off the tomatoes, and all the ingredients should be extremely soft and combined. Remove pot from heat and blend the sauce with your immersion blender until completely blended through. Add in the chopped basil and stir in.
Allow sauce to cool. You can serve the sauce immediately if desired, but after a night in the fridge the flavours really develop. Place in mason jars and store in fridge. Enjoy!!