It is a philosophy Iranians once shared with most of the civilized world, including China and India and the medieval West, where it was called the Salerno Regimen, after the city whose physicians taught it. It still affects the way foods are combined and served. The philosophy rests on the belief that the body reflects the elements of earth, air, fire, and water in humors-blood, yellow bile, phlegm, and black bile. Proper diet is the way to bring the humors into balance. Foods are classified as hot, cold, wet, and dry, measurements not of temperature but of energy.
Hot foods are high in it, cold foods low.
The everyday ideal, though, is balanced dishes, suitable to the occasion. Another reason, of course, is that those ingredients taste absolutely wonderful together. She has spent the last 20 years cooking, researching and collecting authentic Persian recipes. She is currently working on a vegetarian cookbook. Jessica's Biscuit is probably the best specialist cookbook site.