We keep several bags in our freezer and collect everything from onions and celery to asparagus, broccoli stems and peppers. Once we have about two large bags worth, I dump them all in a pot, cover them with water and make some stock. I will also add a couple of bay leaves if I have them, along with any fresh herbs on their way out. I used to put them all in a large stock pot and simmer covered for at least 3 hours. Now I've discovered I can do this all much more quickly and get more than twice the flavor by using my pressure cooker. Just lock the lid, turn the burner to high and begin to steam. Turn down the temp to low for about 20-30 minutes and let slowly cool until you can open the steamer. Once it cools, I strain it into another large pot and then portion it out into different-sized containers so I have anywhere from a cup to a quart to use for recipes. I let it cool on the counter, move to the frig and then the freezer once cold. It's exciting to taste the variation each time since it's different depending on the veggies you had in the bag. The best part is that there is no added anything and, if you buy organic veggies (or at least the dirty dozen ones) then you can pronounce everything in your stock.
*Variations we've made: Add chicken bones to your freezer bag.
For chicken soup, add 2 skinless, split chicken breasts (bones on). Remove the chicken breasts once you can open the pressure cooker and let cool. Take meat off the bone and shred into strained stock.
Veggie soup: chop onions, celery, carrots and add to simmering stock. Add spices (thyme is my favorite) and lentils, brown rice or Bob's Red Mill veggie soup mix http://www.bobsredmill.com/vegi-soup-mix.html.
Just be sure and cook these separate first so they don't soak up all of your stock.
