Clean and prep the vegetables (white onion, leeks, carrots, celery, and parsnip).
Heat up some (extra virgin) olive oil in a big soup pot and cook the vegetables for about 5 minutes, before you add water, salt and the herbs . Note the more water you add the less concentrated your stock will be.
Once you have added the water and herbs, bring it to the boil and let it simmer for 30 minutes (or a bit longer if you like). Strain the stock through a fine sieve, or a cheese cloth.
Use the vegetable stock immediately, or let it cool down and freeze it down for when you are ready to use it.