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–+ servings
A bowl of roasted vegetable broth.
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The Best Slow Cooker Roasted Vegetable Stock

This herb and wine infused vegetable stock is made rich and savory by first roasting the vegetables in the oven, and then letting the slow cooker work its low and steady heat magic, hands off with no hovering. Full-bodied and savory, it makes a great base for brothy Asian and simple vegetable soups.
Prep Time 15 minutes
Cook Time 10 hours
Total Time 10 hours 15 minutes
Servings 2 quarts
Author Karen Gibson

Ingredients

roast the vegetables

  • 2 sweet onions peeled and quartered
  • 2 portobella mushroom caps gills scraped, sliced thick
  • 3 ribs celery with leaves roughly chopped
  • 1 medium parsnip roughly chopped
  • 1 red bell pepper stems and seeds removed, cut into 2” pieces
  • 3 cloves garlic unpeeled
  • 2 tablespoons extra virgin olive oil
  • 1/2 cup red wine

prepare the stock

  • 1 tablespoon tomato paste
  • 1 sprig rosemary
  • 4 sprigs thyme
  • 1 bunch flat-leaf parsley
  • 2 dried bay leaves
  • 1 teaspoon whole peppercorns black and red is a nice combo
  • 1 1- inch x 2-inch piece parmesan cheese rind optional
  • 2 big pinches coarse sea salt
  • 8 cups water

Instructions

  • Preheat oven to 450°F.
  • Place vegetables and mushrooms in a large, unlined roasting pan and toss lightly with olive oil, spreading them out evenly in the pan in a single layer. Roast for 20 to 30 minutes. Transfer to slow cooker and turn heat to Low (or 8 to 10 hours). Add tomato paste, herbs, peppercorns, optional cheese rind, salt and water.
  • Add wine to the still-very-hot roasting pan and deglaze, scraping up as much of the browned vegetables bits as you can, and simmer until most of the wine has evaporated. Add everything - bits and juices - to the slow cooker and give the stock a quick stir. Cover and cook the stock for 8 to 10 hours on Low.
  • Scoop the vegetables into a sieve or fine-mesh colander, and drain the vegetables into a large bowl, pressing firmly on the vegetables to extract every last drop of juice. Remove the spent vegetables to another container (or discard). Then strain the liquids from the slow cooker through a fine sieve into the large bowl, too.
  • Use the strained broth immediately, store in the fridge for one week, or freeze for up to 4 months.