stock from vegetable trimmings

I first read about this idea in the The Locavore's Handbook.  Instead of going into the compost pile, you can save your vegetable trimmings in a bag in the freezer.  When you fill it, simmer the contents on the stove for a half hour.  You then have stock for soups or risotto.  Its a great way to utilize all of those small center pieces or garlic (no peeling needed), celery greens, or parmesean rinds.

Here is a great article about this on the Portland Farmer's Market blog.