Season chicken and brown in oil in a large heavy pot. Add onions and tomatoes. In separate pot heat chicken stock and whisk in tomato paste. Thin peanut butter slightly with hot liquid and add all liquids to pot with chicken. Reduce heat and simmer 30 minutes. Add vegetables and cook until chicken and vegetables are tender, approximately 45 minutes. Season to taste with salt, cayenne and ground white pepper. Garnish with peanuts.