Sauté onions and garlic in olive oil until soft.
Add tomatoes, and sweet potato to the saucepan.
Stir and cook for 5 minutes.
Add stock and cayenne pepper or chilli powder.
Cover and bring to the boil.
Reduce heat to medium-low and simmer for 15 to 20 minutes or until potato is tender.
Remove from heat and allow to cool slightly.
Blend until smooth in a blender or with a stick blender.
Serving Size 1 cup
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.