I am unable to eat tomatoes. What can I use instead, especially in soups?
There is an alternate product available that does not contain tomatoes. It is called  Nomato .
It is described on the home page as:

Nomato sauces are a delicious natural alternative to traditional tomato based products.

Additional info:

Nomato may be substituted in any recipe using tomato sauce, barbecue sauce, ketchup or salsa.
Nomato is made from vegetables and seasonings. It contains no soy, dairy, wheat, gluten, nuts and of course no tomatoes!

I am not promoting this product and, quite frankly, have not tried it. However, I did read several great reviews about it.