For the slow cooker or stove top, this recipe makes 4 cups; can be frozen.
8 stuffing mushrooms (or 3 large portobello caps), cut in half3 stalks celery, cut in half cross-wise
3 medium carrots, ends trimmed, cut in half cross-wise
2 parsnips, peeled, cut in half cross-wise
3 large leeks, white part only, washed, cut in half cross-wise
1 large tomato, cut in quarters
6 whole cloves garlic, peeled
4 tsp olive oil
A pinch each of kosher salt and fresh black pepper.
1/4 tsp dried thyme leaf
1 large bay leaf
1/2 tsp mushroom
powder*
1/2 tsp tomato powder
or 1 tsp tomato paste (optional)
1/2 tsp kosher salt
1/4 tsp
fresh black pepper
Preheat oven to 375°F.
Place all of the vegetables on a rimmed sheet pan. Drizzle with olive oil and season with salt and pepper. Toss, and spread the vegetables evenly on the pan. Roast for 45 minutes, until the vegetables are browned.
Place roasted vegetables in 4-quart slow cooker, and add remaining ingredients. Cover with 5 cups of water. Cook on HIGH for 2 hours. (To make on the stove top, place ingredients in a small Dutch oven or heavy pot, and bring to a boil. Lower heat to low and cook, covered, for 1 hour.) Remove and discard the vegetables. Taste the broth and add salt and pepper as needed. Cook for an additional 30 minutes. Pour through a fine-mesh strainer into a storage container. Use immediately, or chill and freeze for future use.
*To make mushroom powder, place dried wild mushrooms (porcini, cepes, etc.) in a mini-food processor and pulse until powdery. You can make this ahead and store in an airtight container or in the freezer.