There are several "red flags" I see in this recipe.  First of all there are a lot of added vegetables for the amount of tomatoes for a water bath process.  The tomato/vegetable juice recipe recommends 22# of tomatoes plus 3 cups chopped veggies such as onions, celery and carrots.  The processing time of 15 minutes is very outdated.  Tomato varieties and densities have changed over the years and so have the processing times which have been lengthened to 45 minutes for quarts for many of the tomato products and even some as much as 85 minutes.  Also adding flour and butter to canned recipes is not safe.  It changes the density and the way heat penetrates.  Most tomato product recipes today are acidified with bottled lemon juice, citric acid or vinegar to assure that the pH falls in the high acid category in order to safely be processed in a boiling water canner.   

I would recommend freezing your soup.  You might want to freeze the tomato mixture and then when thawed add the flour and butter when heating.

Thanks for using Ask Extension

Nellie Oehler