Vegetarian African Sweet Potato and Peanut Soup (thanks Karen-Anne Thomson)

This is a vegetarian version of African Sweet Potato and Peanut Soup. After making it the first time, I cut back on the cumin as I personally found it to be too strong.  

1 tbsp vegetable oil
1 large onion, chopped
2 cloves garlic, minced2 tsp minced fresh ginger root
1 ½ tsp ground cumin
1 ½ tsp ground coriander
½ tsp ground cinnamon
1 pinch ground cloves
3 medium tomatoes, chopped
1 ½ lbs sweet potatoes, peeled and chopped
1 carrot, peeled and chopped
4 ½ c water
1 tsp salt
¼ c chopped, unsalted, dry-roasted peanuts
1 pinch cayenne pepper
2 tbsp creamy peanut butter
1 bunch chopped fresh cilantro (optional)

Heat the oil in a large saucepan over medium high heat. Saute the onion 10 min until lightly browned. Mix in the garlic, ginger, cumin, coriander, cinnamon and cloves. Stir in the tomatoes, sweet potatoes and carrot and continue to cook and stir about 5 min. Pour water into the saucepan and season the mixture with salt.  Bring to a boil, reduce heat and simmer 30 min. Remove from heat and in a food processor or blender, blend the soup with peanuts until almost smooth. Season with cayenne pepper. Return to the saucepan, whisk in the peanut butter and cook until heated through. Serve warm with fresh cilantro.