Making a big batch of vegetable stock is a great way to clear out the vegetable crisper in times of garden plenty. But this particular recipe is also worth going out and buying fresh veg for to put away in freezer containers for use all winter.
While it's true that all kinds of vegetable scraps can be boiled to make vegetable stock, the goal here is to achieve an appealing flavour, fragrance, and colour. That means leaving out some of the stronger flavoured vegetables, and keeping in some particularly complementary ones. Broccoli and the other Brassicas have a little too much funk. Beet root tends to dominate vegetable stock in both colour and flavour. Start by making a rich, but neutral stock, and then add in the other vegetables to make a specific vegetable soup like broccoli or beet soup. Here is our Best Vegetable Stock recipe.
2 yellow (or Spanish) onions, thinly sliced
6 carrots, thinly sliced
1/2 celery head, thinly chopped from the leaf end, including leaves
1 whole garlic bulb, sliced in cross section
5 sprigs Italian parsley
1 Tbsp yellow miso (optional)
2 leaves dried kombu (optional)
3 dried Shiitake mushrooms (optional)
1/4 cup vegetable oil
1 tsp kosher salt
6 quarts cold water
Preheat oven to 350°F.
To capture the maximum flavour, first chop all the vegetables into fine slices. A mandoline works well. Chopping finely maximizes the surface area of the vegetables, which improves the amount of potential caramelization in the oven. The optional miso, kombu, and dried Shiitake mushrooms add umami and a whole depth of flavour. If using, water down the miso and incorporate it into the vegetable pieces. Then drizzle over the oil and work it in so that almost all surfaces of the vegetable pieces are coated.
Spread the vegetables out on a rimmed baking sheet and sprinkle with salt. Roast in the centre of the oven for 30-45 minutes. Some of the vegetables should definitely become caramelized (charred) for the best flavour.
Once roasted, place the vegetables in a large stock pot, and cover with cold water. Bring to a boil over high heat, and then reduce to simmer, partially covered, for 30 minutes. Remove the lid and allow the stock to reduce by a third to concentrate flavours. Allow everything to cool down before straining the stock through a fine sieve. This stock keeps well in the freezer.