Question: what can be substituted for 15 ounces of tomato sauce?
Answer: Tomato paste serves as the easiest substitute for tomato sauce. ... 
One can substitute canned tomatoes for the sauce by blending 1 cup canned, stewed tomatoes with water until it reaches a smooth consistency.
Tomato juice is a good sauce substitute. ... 
An extremely handy substitute for tomato sauce is puree.