Peel the celery and cut it into chunks. Clean the leek, wash it thoroughly, slice it in half, cut off the green ends and the root end, and wash it again. Slice the leeks.2. Warm olive oil in a large Dutch oven or soup pot over medium-low heat. Add the leeks and a generous pinch of salt. Cook slowly for about 8–10 minutes, stirring occasionally, until they are soft and sweet.3. Add the garlic and chopped fresh thyme and cook for another minute.4. Add the celeriac, onion granules and vegetable broth. Bring everything to a boil, then reduce the heat to medium and cook until the celeriac is completely tender, about 20–25 minutes.5. Cool for 15 minutes. Blend the soup until completely smooth. Taste it before adding the dairy or coconut milk. This is where I usually realize it needs just a little more salt.6. Stir in the crème fraîche and heavy cream. Add the apple cider vinegar a little at a time. Start small so you dont make the soup taste like vinegar. Taste again and adjust the seasoning.