Heat 2 tablespoons of butter in a large heavy skillet. Add chicken pieces and brown well on all sides. Remove from pan. Add onion and carrot to same pan and sauté until brown. Add the remaining butter and leeks, sauté briefly, then lay chicken pieces on top of vegetables. Sprinkle with salt, paprika and pepper. Pour apple juice over chicken. Cover and cook for 35 minutes over low heat. Add the tomatoes and mushrooms to stew the final 10 minutes of cooking time. Sprinkle with chopped chives and serve with brown or white rice. Serves 4