Cover the pan, reduce the heat & let the sauce simmer for 10-15 minutes, stirring occasionally.
Pour the sauce into a blender or use a hand-held blender to blend the sauce until it is smooth. You can adjust the consistency of the sauce by adding water and tomato paste.
Return the sauce to the pan and let it simmer for an additional 10-15 minutes.
Season the sauce to taste.
Recipe by Itsy Bitsy Foodies at http://itsybitsyfoodies.com/marinara-sauce/