Bring water and bouillon to a gentle boil. Peel and coarsely chop sweet potatoes, onion, carrots and tomatoes. Add to boiling water. Simmer covered for 3 to 4 hours stirring ocassionally until sweet potatoes are really soft then simmer uncovered for the last hour so the soup thickens. Add remaining ingredients to taste and stir.
This could also be made in a slow cooker on low and the next time I make it I plan to try that.
Serve piping hot with a dollop of sour cream and a sprinkle of bacon bits and chives and home made bread or biscuits and a salad.
Vegan version: substitute vegetable broth for chicken bouillon or use plain water.