ok, all measurements are approximate.
You can make any kind of cream soup this way; potato, celery, mushroom, chicken, clam, broccoli, carrot, pumpkin, squash, whatever.
2-3T fat or oil (whatever is appropriate for your other ingredients)
1 small onion, diced
2 stalks celery, diced (I chop these super fine in the processor b/c I like smooth soup)
4-6 c stock or broth (I usually use chicken, but fish, clam, beef, can be used, too)
1 T dried thyme leaves (or a lot of fresh)
1/2-1 c cream (you CAN use milk, but I never do)
2 T cooking sherry or wine
salt and pepper
Saute onion and celery in the fat or oil(you can add bacon, here, too if you want). When the oil starts to separate from the onion/celery mixture, stir in enough flour to absorb all the oil. Let cook on medium w/o browning, then add the stock or broth all at once. Add your main ingredient,plus the seasoning, and cook to desired consistency. Remove part of the cooked vegetable to the food processor and add cream; puree together, then stir back into the remaining soup. Heat a bit more, but do not boil. Taste and re-season if necessary.
For mushroom soup, I saute the mushrooms w/ the onion and celery. If you want to add ham, do it during the last re-heat after stirring in the pureed portion. :)
Please post any questions below.