Hi. There are dozens of ways to use up odds and ends of ingredients; in fact, I did one last night myself. I made chicken just for this, although you could use leftover. And I omitted the scallions and spinach called for and used shredded cucumbers and bits of extra bell peppers instead: http://www.rachaelray.com/recipe/col...satay-noodles/
Here's how to make a vegetable soup without a recipe: http://www.epicurious.com/recipes-me...e-soup-article
You can add chopped chicken or beef to this, and you can leave the veggies chunky if you'd rather not purée it.
There used to be blogging events where people would make food according to a theme and then post on their blog what they did. Then the hostess would post a round-up of all the submitted recipes. Here's the beginning of one called Leftover Tuesdays; it went on weekly for months, so you can search the site for more ideas: http://www.epicurious.com/recipes-me...e-soup-article
Hope this helps.