Make sure leeks are washed well first.
Heat the oil, butter and a pinch of salt in a large pot over medium heat.
Add the leeks & onion, sauté until softened, about 5-6 minutes.
Add the potatoes, garlic, thyme, rosemary, and coriander. Sauté for 2-3 minutes.
Add the vegetable broth, bay leaf, salt, and pepper. Raise heat so it starts to simmer.
Reduce heat to a low simmer and cook for about 15-20 minutes, or until the potatoes are fork tender.
Remove from heat and remove bay leaves.
Stir in the coconut milk and optional lemon juice. Taste for seasoning and add more to taste.
Using an immersion blender, blend until smooth and creamy. You can also use a regular blender and carefully blend in batches.
Before blending, set aside a few pieces of potato for the garnish.
Serve in soup bowls and top with chopped green onion, fresh ground pepper and a few pieces of cooked potato.
