Heat some oil in a heavy pot or Dutch oven until very hot. Generously brown the chicken pieces on all sides (crucial for the flavor of the sauce). Remove the chicken.
In the same pot, add some more oil and cook the onions until caramelized. Add the remaining ingredients and bring to a simmer, stirring until the peanut butter is fully incorporated. Return the chicken to the sauce, nestling it in the sauce. Cover and simmer over low for at least one hour. Add salt and pepper to taste.
Serve with steamed rice or African fufu (see blog post for explanation).
**This dish tastes even better the next day after the flavors have had more time to meld.