In a large pot, mix soup and diced tomatoes with water.
Add oregano and basil;bring to a boil, then reduce heat to simmer.
Meanwhile, bring another pot of water to boil.
Add tortellini and cook until pasta rises to the top of the water; drain.
Add tortellini to tomato soup.
Stir to heat through.
Top each serving with 1 tsp. Parmesan cheese.