If it wasn't raining I would have already thrown this out ... but I went in and dug through the trash ....
A can of condensed tomato soup has about 24g of sugar (some have more). A teaspoon of granulated sugar is 4g. So ... if I cypher this right ... a can of tomato soup is about 2-TABLESPOONS of suger.
Now, if the recipe was the same except for the addition of carrots ... I can't see where more than about a teaspoon, or two at most, of vinegar would be needed to bring the acid-sugar ratio back into the "before carrots" balance.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain