What's the key to making thick soups?
Make your favorite vegetable soup.  Remove 1/4 and puree in blender.  Return to the rest of the soup.  If it is not yet think enough, increase the amount you remove and puree until you find the consistency you are looking for.  If you don't have a blender, you can use an immersion "stick" blender, or even a hand cranked food mill. Alternately, if you have none of these devices, simply put the veg. in a bowl and mash with a potato masher.