1 medium onion, sliced
1 (14 1/2 oz) can vegetable broth (or homemade)
1/4 tsp salt
1/4 tsp cayenne
1/4 cup smooth peanut butter
2 Tb chopped cilantro or parsley
In a medium soup pot or large saucepan, combine the yams, onion, broth, salt, cayenne, and 1 3/4 cup water. Bring to a boil, reduce the heat to medium, cover and cook until the yams are very soft when pierced with a fork, 10 to 15 minutes.
With a slotted spoon, remove the yams and onions to a food processor. Puree in batches until smooth, adding extra liquid as necessary from the soup pot.
Whisk the peanut butter into the remaining stock in the pot. Using a rubber spatula, scrape the yam puree back into the soup pot. Reheat, stirring to mix well. Season with additional salt and cayenne to taste. Garnish with cilantro or parsley.