I always have homemade vegetable broth stashed in my freezer. I freeze the broth in an ice cube tray and then store the cubes in freezer-safe containers in the freezer. Make sure to note now much broth your tray holds, so you know how many cubes to use when cooking. (With my tray, eight ice cubes equals 1 cup [240 ml] of broth.)
I purposefully keep my vegetable broth very light on salt. This allows me to control how much salt I'm using so I don't end up with an oversalted soup.
Preheat the oven to 400°F (200°C]. Place the carrots, onions. celery, garlic, and mushrooms on a baking sheet and toss to coat with the oil and ¼ tsp of the salt. Roast for 45 minutes, or until soft and browned.
Transfer the roasted vegetables into a large Dutch oven or stockpot (make sure to scrape up and add any browned bits that are stuck to the pan). Add 4 qt [3.8 L] of water, the parsley, thyme, peppercorns, tomato paste, bay leaves, and the remaining ¼ tsp of the salt. Bring to a boil over high heat and then lower the heat to medium-low and simmer for 1 hour to develop the flavor.
Strain the broth through a fine-mesh strainer into a heatproof bowl. Discard the cooked vegetables and herbs. Use right away or let the broth cool slightly before transferring to airtight containers in the fridge or freezer.
Makes about 9 cups [2.1 L]
4 carrots, peeled and cut into 172 in 4 cm pieces
2 yellow onions, peeled and quartered
5 celery stalks, cut into 1½ in [4 cm] pieces
1 garlic head, halved crosswise so the cloves are visible
1 1b [455 g] white button mushrooms, halved
1 tsp olive oil
1 tsp salt
1 bunch fresh parsley
5 thyme sprigs
1 Tbsp black peppercorns
1 Tsp tomato paste
2 bay leaves