Start by taking your large stockpot or pressure cooker and adding all the ingredients: the halved onions, quartered carrots, quartered celery, halved garlic, thyme, parsley, bay leaves, and the tomato paste. Pour in about 3 quarts of water to cover the vegetables completely. This combination will create a flavor-packed base.
For the next step, if you’re using a stockpot, bring the mixture to a boil over medium-high heat. Keep an eye on it, as you want to ensure it doesn’t boil over. Once boiling, reduce the heat and let it simmer. If you’re using a pressure cooker, seal the lid and set it to high pressure for 30 minutes. This method will extract maximum flavor from the vegetables.
After your stock has simmered or pressure-cooked, it’s time to release the pressure if you're using a pressure cooker. Allow it to naturally release for about 10 minutes before carefully quick-releasing any remaining steam. Open the lid and take in that glorious aroma from the fresh ingredients.
Let the stock cool slightly until it’s easier to handle. Using a slotted spoon, remove the larger vegetable pieces and discard them. You can also strain the remaining broth through a fine-mesh strainer for a clear broth. For an even clearer stock, consider straining it twice.
Once strained, pour the broth into storage containers, allowing it to cool completely before sealing. Homemade Vegetable Stock can be stored in the refrigerator for up to 5 days. If you don’t use it within that time, you can bring it to a boil before using it again.
As you cool the broth, think about adding salt to taste. This can be done before storing or when using the stock in your recipes. This step is essential, as it allows you to season the stock to your liking.