Dice the tomatoes, and chop up the remaining veggies. Put everything except the peanut butter into a pot with some water, tomato juice, or veg stock and boil away until you have reach a suitably soft consistency. Once softened, add the peanut butter (I guess you could use peanuts instead) until it mixes in a bit and puree.
The mixture of the sweetness and spicyness to great. My friend who told me about this recipe says it is of African origin, but I have no facts to corraborate this except for frequent mentions of yams and peanuts in African literature.
Sorry, I don't know the nutritional info, but all the fat comes from the peanuts and there is no added salt necessary.