Heat large pot over medium heat and add the onion, garlic and ginger and cook for 3 minutes. Add a tad bit of water if things start to stick to the pan.
Add the sweet potatoes, tomatoes, water, cumin powder, cinnamon, chili powder, sea salt and stir.
Place a lid on the pot and cook for 20 minutes, stirring occasionally seeing that nothing sticks to the bottom of the pot.
After 20 minutes, take off the lid, turn off the heat and allow to cool for 15 minutes.
Blend the soup in batches along with the coconut milk until all the soup is creamy and smooth.
Garnish with cilantro.