I have learned from experience that making your own vegetable stock for your soups makes a huge difference in the depth of flavor. Bouillon cubes and store-bought stock just don't stand up to the complex-yet-subtle flavors you can create on your own! As you're preparing your veggies for your soups, simply start another pot on the stove. Put in some water (however much you'll need for the stock, plus a bit extra to account for evaporation). Add the following bits and pieces to the stockpot as you clean and chop: roots/greens of leeks; the small/hard-to-peel garlic cloves; potato parings (wash first!); winter squash skins; carrot peels; chard stems (if you don't want them to go in the soup itself); parsley stems; and so on. There are a few essentials you should always add, if you have them (carrots, celery, onions, thyme, parsley, bay leaves, garlic, salt, and oil). There are also some ingredients to avoid adding (turnips; rutabagas; cabbages; Brussels sprouts; red beets -- unless you're making a beet soup; tiny celery seeds; powdered herbs; ground pepper; onion skins; artichoke trimmings; more than four cups of greens; funky/spoiled veggies). Other than these must-avoids, you can go to town with adding clean bits and pieces to the stockpot. Remember: the more veggies you use, the richer the flavor will be. When you're ready to add the stock to your soup, strain it first. Add to the soup pot and adjust seasonings, as necessary. --Molly Here's a little guide I made for my housemates to put on the fridge door as a reminder for making stock each time we cook!
Thanks to Deborah Madison's Vegetarian Cooking for Everyone for these lists and ideas!
For those of you who need a bit more structure, here are some recipes:
Basic Light Vegetable Broth adapted from The New Vegetarian Epicure by Anna Thomas 5 large carrots (1.5 cups sliced) 2 large celery stalks (1.5 cups sliced) 2 large onions 1 head garlic green top of 1 large leek (2-3 cups sliced) thick peels of 2 small potatoes 1 turnip or rutabaga 1 bay leaf 1 tsp. dried thyme (or 1 Tbsp. fresh) 1 tsp. black peppercorns 4 branches flat-leaf parsley 12 branches cilantro 1.5 tsp. salt 12 cups water
Wash all veggies thoroughly. Scrape the carrots and peel the onions. Thickly peel the potatoes, reserving the inside for another use.
Slice or coarsely chop everything except the head of garlic, which can just be sliced crosswise and put in as-is.
Combine all the veggies, herbs, and seasonings with the water in a large pot. The water should just cover everything when you first put it all together.
Bring the water to a boil, lower the heat, and let the broth boil gently for about 45 minutes. All the veggies should be completely soft, and the flavors fully released into the liquid.
Strain the broth through a colander, then through a fine sieve to remove any sediment or cloudiness.
Taste and correct the salt, as needed, bearing in mind it's often best to leave a broth unsalted until you know how you're going to use it.
Variations:
Brown the veggies before adding them to the stock. This will make it a richer, heartier broth.
Add any of the following items to change the above recipe, as needed (to make it more seasonal or to simply add what you have on hand): chard leaves and stems tomatoes kale leaves and stems broccoli stems and leaves mushrooms green onions fennel (bulb and/or fronds) summer squash/zuccini peeled winter squash celery root parsnips