This is a traditional West African soup recipe. The main ingredient is chicken that's flavored with peanuts and sweet potatoes, and it gets additional seasoning depth from fresh ginger, garlic, chilies and kale. It's quite delicious and, once your try it, it's likely to be a regular feature at your home.
Chop peanuts, or crush them with the side of a knife, or pulse them in a food processor to chop roughly.
Put oil in a deep skillet or medium saucepan over medium heat; a minute later, add onion, ginger and garlic and cook, stirring occasionally, until onion is soft, 3 to 5 minutes. Add chicken and continue cooking for another 3 or 4 minutes, until just coloring. Add 1/2 cup peanuts and the cayenne and sprinkle with salt and pepper.
Stir in the stock 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 1/4 cup peanut butter. Taste, adjust seasoning (you may want to add more peanut butter at this point) and serve, garnished with remaining peanuts.