from Martha Stewart
Stock Up on Scraps
Reserve carrot ends and peelings, celery leaves, garlic trimmings, the outer layers of onions, and wilting herbs and their bare stems (such as parsley and thyme) in a resealable bag. Store shrimp shells or roast-chicken bones separately. Freeze, then make stock from scratch whenever the mood strikes (Tip: Remove onion skins before using; they can turn a perfect stock into a bitter one).
Vegetable broth recipe
Are you looking for a recipe for homemade vegetable broth? Well, here it is: Throw a bunch of vegetables (scraps, skins, whatever) in a big pot with some water, salt, and pepper, and let it simmer for a while. Then strain it.
You just made homemade vegetable broth.