Chicken and Vegetables Braised in Peanut Sauce

Name: Chicken and Vegetables Braised in Peanut Sauce
Ingredients: 1 1/2 cups unsalted roasted peanuts (1/2 lb) or 1 cup all natural creamy peanut butter; 3 cups water; 4 1/2 to 5 1/2 lb chicken pieces such as drumsticks, thighs, and breast halves; 2 tablespoons vegetable oil; 1 medium onion, chopped; 1 red bell pepper, chopped; 3 garlic cloves, finely chopped; 1 (14- to 16-oz) can diced tomatoes including juice; 1 to 1 1/2 teaspoons cayenne; 2 teaspoons salt; 1 1/2 lb sweet potatoes (2 medium), peeled and cut into 1-inch pieces; 4 medium turnips (1 lb), peeled if desired, halved horizontally, and cut into 3/4-inch wedges; 1 lb spinach, coarse stems discarded; Accompaniment: white rice