Heat the olive oil in a large pot. Add the shallots, garlic, ginger, turmeric and cinnamon. Sauté over low heat for 7 minutes until softened.
Add the sweet potatoes, carrot and tomato purée. Season with salt and pepper and stir to combine.
Add the lentils, stock and coconut milk and bring to a rolling boil. Lower the heat and simmer for 20 minutes.
Break up the sweet potatoes using the back of a wooden spoon or liquify two ladlefuls of the soup in a blender and then add back into the soup, stirring it in.
Add the chopped kale, cover the pot and continue to cook for another 10-15 minutes, stirring occasionally. If the soup is too thick you can add a little hot water to thin it out.
Stir in the vinegar and check the seasoning.
Serve with a pinch of dried chilli flakes and add a drizzle of olive oil and vinegar.
• If you don't have coconut milk you can use 4 1/2 cups of vegetable stock instead. • You might need to add extra liquid when reheating the soup as it will become very thick if stored. • You can also use butternut squash instead of the sweet potato. • You can use cavolo nero instead of Kale - it might need a little less cooking.