From lasagna to tamales, turn just about any dish into a main course soup

We often think of soups as merely a side dish or a last-ditch effort to use up leftovers, but don't overlook main-course soups that are inspired by main courses.

We've all heard of tortilla soup, meatball soup, baked potato soup or sweet potato soup topped with bacon and sour cream, but soup made with leftover barbecue ribs? Sally Swift is on it.

"Take the meat off the bone, just like a ham," says the longtime producer of "The Splendid Table," the weekly radio food show that airs locally on KUT. Add chicken stock, a can of tomatoes and leftover pinto beans in a pot and bring to a simmer. "And there's no reason you couldn't top it off with a vinegary coleslaw as a garnish."

No matter if you're talking lasagna or spring rolls, there's probably a way to turn your favorite dish into a soup. You can add chicken, beef and/or vegetable broths to just about any set of ingredients; the trick is to get the right proportion of liquid, fat, vegetables, proteins and starches like rice or noodles.

In some ways, all soups are reflections of liquid-less dishes: Chicken and rice, lentils, seven bean. But others, like cheeseburger soup, push the limits. Do you really need to throw a perfectly good cheeseburger into a soup pot? No, but sometimes you're in the mood for a change, and ground beef and a block of cheese might be the only things in your fridge.

Then there's a whole slew of soups in between. On page D8, we have recipes for soups inspired by lasagna, yam curry and plate of kielbasa, kale and potatoes, but you could take the idea and apply it to just about any casserole or main course in your recipe box. The key is breaking down a meal into its parts and then reassembling them with more liquid. Some of the less soup-friendly ingredients, like cheeses, breads and salad greens, can be added as garnishes right before serving. (See below right for a recipe for croutons that you can make with a regular old loaf of sliced wheat bread.) Starches overcook in an instant, so I prefer to cook the pasta or rice separately and then add to each individual serving, just before the garnishes or toppings.

The flavors and textures of a corn casserole can translate into a chunky corn chowder-like soup that you could top with diced ham. Throw roasted vegetables with vegetable stock into a food processor or blender — or use that new immersion blender you got for Christmas — and serve in a bread bowl with a spoonful of sour cream. Leave it to Second Bar and Kitchen chef David Bull to make a pepperoni soup that tastes like pizza in a bowl, which he serves at the restaurant.

Slow-cooker pot roast is only a few cups of broth away from a warming bowl of fragrant soup. "Big braised meats are the perfect thing to turn into a soup because you have all the liquid from the drippings," Swift says. Let the liquid cool and then remove most of the top layer of fat and build your soup from there.

Ruth Ellsworth Carter, a local restaurant consultant and cooking class instructor who spent more than 20 years as the soups-and-sides chef at Eastside Cafe on Manor Road, says she's always thinking of ways to turn other dishes into soups. One of her favorites is a pumpkin ravioli with shiitake soup that she made after eating a similar dish by the famed waterways of Venice on a trip to Italy.

(Carter is teaching a class about how to make better soups at the Savory Spice Shop on West Sixth Street at 6:30 p.m. Monday . To sign up or for more information, call 524-1093 or go to savoryspiceshop.com.)

To cut down on the amount of heavy cream, milk or half and half you are using in creamy soups, Carter recommends thickening with mashed or pureed potatoes instead. Other thickeners to keep in mind as you think about building your soups: roux (three parts flour cooked in two parts fat); cornstarch or corn masa blended with a little water; or even pureed corn tortillas or toasted nuts. Flour tortillas or other flour-based dumplings also will thicken your soup.

Overcooked vegetables can sink a soup, and Carter recommends adding vegetables according to how long they take to cook. For instance, carrots would go in before zucchini. She'll sometimes even take out some of the vegetables that she put in at the beginning, so they've added flavor to the broth but won't take away from the final overall texture.