Chop the onion into fine pieces, crush the garlic and fry in the olive oil in a large stew pot till soft. Add the Bay leafs, thyme, crushed red pepper flakes, cinnamon and grated whole nutmeg and fry for a minute, keep stirring to avoid burning.

Add the water, tomato puree, arrow root and the water. Bring to the boil.

Peel and chop the yam into large 1 inch size cubes and add to the boiling liquid pot. Allow the yam to soften almost completely. Peeled and chopped the sweet potato into 1 inch cubes and add to the pot.

Simmer for around an hour till the liquid to reduce and thick.