West African Peanut Soup with Chicken

From Mark Bittman, The Minimalist, New York Times 6-17-09

¾ cup roasted and shelled peanuts	Salt and freshly ground pepper
2 Tblsp peanut or neutral oil	6 cups stock or water
1 medium onion, chopped	2 sweet potatoes (about 1 lb)
1 Tblsp minced fresh ginger	8 plum tomatoes, cored and halved (drained canned tomatoes are fine
1 Tblsp minced garlic	½ lb collards, kale or other greens, washed and cut into wide ribbons
½ lb skinless, boneless chicken cut into chunks	¼ to ½ cup peanut butter
Pinch of cayenne

1. Chop or crush peanuts.

2. Heat oil in 3-4 quart saucepan or deep skillet over medium heat; add onion, ginger and garlic and cook, stirring occasionally, until onion is soft, 3-5 minutes. Add chicken and cook for another 3-4 minutes, until just coloring. Add ½ cup peanuts and the cayenne and sprinkle with salt and pepper.

3. Stir in the stock or water and the sweet potatoes, bring to a boil, and turn heat down to medium-low so the soup bubbles gently. Stir in tomatoes and collards, then cook, stirring occasionally, until chicken is cooked through, about 10 minutes.

Stir in ¼ cup peanut butter. Taste, adjust seasoning, and add more peanut butter if desired. Garnish with remaining chopped peanuts