Place the solid cooking fat in a soup pot on medium heat. When the fat has melted and the pot is hot, add the leeks. Cook, stirring occasionally, about 5 minutes, or until the leeks have softened and browned a bit.
Add the broth, water, vinegar, parsnips, thyme, and salt to the pot. Bring to a boil, cover, and turn down to a bare simmer on low. Cook for 15 minutes, until the parsnips are fork-tender. Turn off the heat and allow to cool for 10-15 minutes.
When the mixture is cool enough to handle, add the lemon juice and blend in either a blender or an immersion blender.
If the mixture cooled too much before blending, give it a re-heat before serving with olive oil and chives.
Recipe by Autoimmune Wellness at https://autoimmunewellness.com/parsnip-leek-soup/