In a large skillet, sauté onion in olive oil over medium heat until onions are tender and translucent. Add garlic and continue to cook for about a minute.
Pour in blended tomatoes and stir. Bring to a bubble.
Add in the rest of the ingredients, stir, and allow to simmer for about 20-30 minutes or until sauce has deepened in color and thickened slightly. If your sauce thickens too much, add a bit of water or broth to thin it out.
Set aside until ready to use.