If you aren't from the south odds are you've never had milk gravy or gumbo made with a roux. Roux is the basis for all things rich and thick in southern cooking. Make a roux; add milk and you have gravy for homemade biscuits, meatballs or chicken fried steak. Make roux and add it to any soup to make it thick and add a layer of flavor that is delicious.
5 T. oil (bacon grease, vegetable oil, olive oil, doesn't really matter)
2 LARGE T. flour
salt and pepper to taste
In a small cast iron skillet (preferable) heat oil until very hot; add flour, salt and pepper. Keep a careful eye on the skillet! Stirring often until flour turns a dark peanut brown.
If making gravy turn down heat and add milk at this point and stir A LOT! Working out any lumps.
If adding to soup, just stir it in!