Philip Kennicott visited New Gourna and Cairo in Egypt and Diyarbakir in Turkey to explore historic cooling techniques. Sima Diab photographed them in Egypt. Dec. 28 at 6:30 a.m.

If you want to freeze your turkey curry for another day, cool the sauce down before adding the turkey. Mix the cold leftover turkey with the cold sauce and freeze. Add the spinach on reheating.