PREP: Peel and chop the white sweet potato into evenly sized chunks. Chop any large broccoli florets in half so that all the pieces are about the same size as the sweet potato pieces. Cut the leek in half through the root and carefully rinse out any dirt or grit from between the layers under cold running water, then slice the leek into half moons about a 1/2 inch thick. Peel and dice the onion. Add all the chopped vegetables to a saucepan or dutch oven large enough to have at least an inch of head room at the top.
SIMMER: Pour the chicken broth over the vegetables and add the dried oregano and salt. Bring the liquid to a steady simmer and continue to cook until the vegetables are tender, about 25 minutes.
BLEND: Remove the pan from the heat and add the coconut milk – I like to add it at the end like this so that it doesn’t have a chance to accidentally overheat and separate, plus I find I get a creamier texture this way. Use an immersion blender to carefully puree the soup together until smooth, then taste and add any additional seasonings if you wish. Garnish just before serving with a drizzle of lemon olive oil and some chopped green onion tops and fresh chives. I like to make a double batch of this soup at the weekend and then eat it throughout the week for breakfast: it will easily last a week in the fridge.