Hi Harryf,
When I make soup, I follow this basic process, I heat up some oil, then put in some onion, after the onion is transluscent, then I mix in flour (whatever kind you like). I stir that together and then when the flour is well mixed in with the onions then I add water/broth and all the other ingredients. If it is not thick enough, then I put some flour in a jar, add a bit of COLD water, cover and shake. Then I add that to the soup and that works wonders. If you add warm or hot water to your soup, it will turn into glue (trust me I learned the hard way once making gravy!)