As you can see from the list of optional vegetables, this is a very flexible recipe. You can add more of just about anything to tilt the stock towards the flavor of your soup, or add a component of your soup to help flavor the stock. For example, if you are making a squash soup, you can add the seeds and any innards you've scraped from the squash to the roasting pan.
Roasted Vegetable Stock
makes 4 to 5 cups
1 large yellow onion, skin on, quartered and stuck with two cloves
6 large mushrooms, halved
2 roma tomatoes, halved
1 medium carrot, roughly chopped
3 large cloves of garlic, unpeeled
(optional vegetables: leek greens from one large leek; celery, one or two stalks, rough chopped; red pepper, quartered and seeds removed)
1 cup of wine, see notes
grapeseed or other neutral, oil
2 bay leaves
6-8 whole peppercorns
Preheat oven to 400 degrees.Place the onion, mushrooms, tomatoes, carrot and garlic, and any other vegetables, in a roasting pan. Drizzle with the grapeseed oil and toss to coat the vegetables. Place in the oven, uncovered, and roast for about 45 minutes, stirring occasionally. Watch the vegetables so they don't char (the leek greens will be especially vulnerable.) You are looking for browning and caramelization, not burnt. If some of the vegetables start to char before the others are done, remove them from the roasting pan.
When the vegetables are done, remove from oven and scrape into a 4-quart sauce pan or Dutch oven. Place the roasting pan over a burner (or two, depending on the size of your pan) and add the wine. Bring to a simmer and deglaze the pan, scraping up any stuck bits. Empty the contents of the roasting pan into the pot with the vegetables and add 6 cups of water, the bay leaves and peppercorns. Bring to a simmer and cook gently for about 1/2 hour or so.
Strain through a cheesecloth-lined sieve and use as needed.
• This stock freezes well.
• Use white wine if you want to keep the stock fairly light in color (it will still be brown); use red wine for a deeper hue and slightly deeper flavor.
• This recipe can be easily doubled or tripled, so long as you don't crowd the roasting pan. Use two pans if needed to prevent crowding.
• I leave the skin on the onions to add color. You can remove them if you wish.
• If your pocketbook can afford it, adding fresh shiitake mushrooms at the roasting stage is a good way to add more flavor; a few dried mushrooms at the simmer stage is nice, too.