American recipe using 'a can of tomato sauce'
I pulled out some cans of tomato sauce to answer your questions. The details are listed below, but it looks like they are generally diluted tomato paste with spices. If you can get tomato paste (canned or in a tube), that should get you the consistency that you want. 

The ingredients as listed on the Hunt's brand are: 


  Tomato puree (water, tomato paste),
  water, less than 2% of: salt, citric
  acid, spice, tomato fiber, natural
  flavor


Shop Rite brand (a supermarket house brand) contains:


  Tomato concentrate (water, tomato
  paste), onion powder, garlic powder,
  citric acid, natural flavorings,
  dehydrated bell pepper


And a can of Rokeach brand (a kosher food processor) tomato sauce with mushrooms contains: 


  Tomato puree (tomato paste &amp; water),
  mushroom, modified potato starch,
  peppers, cottonseed oil, sugar, onion,
  apple cider viengar, garlic, celery,
  white pepper, bay leaves and citric
  acid.