In a large pot, heat 1 T olive oil.
Add leeks and celery and stir fry until softened.
Add potatoes and pour broth over to cover.
Add garlic, chives, parsley and seasonings and heat at medium heat for about 30 minutes or until potatoes are very soft.
Slowly stir in yogurt and cream.
Take 1/2 of the soup and transfer into a blender and blend until smooth.
Add mixture back to the pot and stir to combine.
Allow to simmer until ready to serve.