I have some soup-making plans in place, and didn't want to scramble to make stock and then build a soup on top of that, so I got to work tonight. I made my first vegetable stock a few weeks ago, and it is clear to me that there is no reason to buy pre-made stock. Too often, they have strange off-flavors, or taste like a pile of old celery, one-note and not even a delicious note at that.
Mark Bittman's How to Cook Everything again provided the jumping-off point, though the main difference here is that I forgot to buy celery and used a leek instead.
Vegetable Stock (makes around 9 cups):
4 large carrots, diced small
3 medium onions, chopped (don't peel)
1 large potato, chopped
1 leek, well-cleaned and chopped roughly
8 cloves garlic (again, don't peel)
1 package chopped mushrooms
2 medium tomatoes, chopped
1 tbsp. tomato paste
1 end parsley and cilantro each (this can be frozen ahead, once you finish the leaves of a bunch)
Freshly ground black pepper
Prepare all your vegetables.
Heat a large stock pot with 3-4 tbsp. olive oil over medium/medium-high heat. Add the onions, leek, and mushrooms and allow them to saute around 10 minutes, giving them a bit of color. Spoon in the tomato paste and saute for 3 minutes or so. The paste will take on a deeper color. Add in the rest of the vegetables and herbs, followed by 14 cups of water.
Bring the stock to a low simmer, and let it go for at least 30 minutes and up to 2 hours, though you will lose some volume the longer the stock cooks. Add pepper to taste.
Once you've decided the stock is to your liking, turn off the heat and let it cool for at least 20 minutes, so that any spills (and there'll be some) will not scald. Ladle the broth and veggies into a strainer placed over a bowl and press with a spoon or spatula, extruding as much juice and flavor out of the vegetables as possible.
Your broth will store well in the refrigerator for about a week, or you can freeze it and use within 2 months.