Cut ends off Roma tomatoes then chop. Puree in blender or food processor until smooth. This will need to be done in batches because of the volume. Pour into slow cooker.
Add remaining ingredients, except for meat. Set slow cooker to low.
Fry sausages in skillet until seared and browned on the outside. Add to sauce.
Add baked meatballs to sauce. (You can use store-bought meatballs, if desired.)
Cook on low heat for 8 hours, stirring occasionally.
Notes
For a faster recipe, substitute fresh tomatoes with three 28-ounce cans of high-quality crushed tomatoes.If using dried spices, alter the amounts to 1 tablespoon oregano, 1 tablespoon basil and 1/2 tablespoon thyme.To cook on the stovetop, use a large stockpot and simmer gently for 4-6 hours, stirring often.