Heat the oil in a large, heavy bottomed pot over medium heat. Swirl it around.
Add the onions and sauté, stirring often with a wooden spoon, until you have deep brown edges, about 5 minutes.
Add the carrots and celery. Keep sautéing and stirring until the celery is bright green, about 3 minutes.
Add the chopped leeks and garlic and sauté until leeks are bright green, about another 3 minutes.
Add the thyme, parsley, bay leaves, and black peppercorns. Give it all a big stir.
Add a big splash of water and, using the back of your spoon, scrape up all the brown bits and caramelization on the bottom of the pot.
Add the remaining water and stir. Place the lid on top, slightly askew. Bring the vegetable stock to a boil and then simmer for about 30 minutes.
Strain the stock, discarding the solids. Season with salt at this point if you like. Pour the vegetable stock into jars and keep in the fridge for up to 1 week or in the freezer for up to 6 months.
Recipe Notes
If you're making something mushroom-y with your stock, 1-2 cups of mushroom stems is great in this stock. Add them with the leeks and garlic in step 4.
To store in the fridge: Once you've strained the finished stock, allow it to cool completely. Then you can transfer it to sealable jars and keep it in the fridge for up to a week.
To freeze, just remember to leave about an inch of space at the top of the jar/container before placing a lid on top and freezing. Liquid expands when frozen! Vegetable stock keeps in the freezer for up to 6 months.
How to make flavorful vegetable stock for soups, stews, risotto, and all kinds of other dishes! Having a delicious stock base makes all the difference in vegan cooking. Chopping the vegetables small and browning them in the pot boosts the flavor and allows for a shorter 30 minute simmer time.