Heat oil in a saucepan over medium heat.
Add chopped onion garlic and ginger. Saute till the onion becomes soft.
Add celery, apples and potato. Mix well.
Cover the pan and allow the mixture to cook or sweat for 5 minutes over low heat.
Add the stock or water. Simmer the mixture till the potato and celery stalks are cooked.
Allow the mixture to cool a bit. Add celery leaves.
Puree or blend the mixture in a food processor.
Pass the liquid through a sieve. This will help to catch any celery fibres or strings.
Return the soup to the saucepan.
Add salt, pepper, turmeric powder and lemon juice.
Heat the soup gently and NOT to a rolling boil.
Serve hot soup with your favourite bread and lemon slices.