Once blended, pour into a hot nonstick pan with the oil, salt and pepper. Cover and cook until the onions are transparent. Then add in the chopped peppers and fresh basil.
In a large bowl combine the meat, breadcrumbs, cooked vegetable mixture and raw tomatoes. Mix until fully combined (I like to wear food grade rubber gloves for this). Add in a little more of the breadcrumbs it the mixture is too wet).
Form uniform sized meatballs that are about 1.5″ around then set into the crock pot, pour the tomato sauce over them to cover completely.
Add the lid and cook on low for about 3-4 hours or until the meatballs are done. The final cook time will depend on the size of the meatballs and the actual cooking temperature of the crockpot.