Shirin Polo (Sweet Rice with Candied Orange Peel and a Tahdig Crust)

Variations

• Morassa polo: the name means jewelled rice. ko.wikipedia calls shirin polo the simplified version of it. It adds more dried fruit in different colours: barberries, dried apricots, dates.
• The plate in the photograph: an Armenian sweet pilaf, topped with orange peel, almonds, pistachios and raisins and served without its tahdig. The raisins are in the ingredient list as an option for that reason.
• Tahdig of potato or thin bread: thin slices of potato or a sheet of thin bread such as lavash laid on the bottom instead of rice. It lifts out in one piece more easily than rice does.
• A rice for occasions: usual at weddings and birthdays; among Persian Jewish communities it goes with Purim and Passover, and in Ramadan with the iftar.

Tips

• A crust can be built only because the rice was drained. Steaming says of the boiled and drained chelow that "the steam then finishes the grain with no free water left to put anything back". Read from the bottom of the pot, the same sentence is why tahdig works. With no free water down there, the oil at the bottom is not held at the boiling point of water and climbs to frying heat. The rice above cooks in steam, and only the bottom centimetre fries, in the same pot. In an ordinary absorption pot the bottom stays near boiling for as long as any water is left.
• A crust you get and a crust you build. Iraqi dolma says to "raise the heat slightly for the last 10 minutes and the bottom potatoes brown into the dark crust", and paella's socarrat forms once the liquid has gone. Both come at the end of the cooking. A tahdig is laid down first and built for forty minutes, which is why the heat starts at medium and drops to its lowest once the pot sizzles.
• Yogurt and saffron in the bottom layer only. The yogurt glues the bottom grains into one sheet that lifts out without breaking, and brings protein and milk sugar with it, so that layer browns first. None goes in the rice above.
• The sugar never goes in the pot. What sugar does says of caramelisation: "Around 160C it breaks down into colour and bitter aromatics." Mix the sugar into the rice and some of it ends up in the bottom layer, forty minutes at frying heat, where it turns bitter before the crust is done. So the sweet things are candied separately and laid on the finished rice.
• The peel's water is thrown away twice. Soaking discards the water from dried chillies, "where bitterness and grit come out of the seeds and pith". The bitterness in the white pith of orange peel comes out into water the same way, so throwing the water away is throwing the bitterness away. Every further boil takes aroma out with it, which is why it stops at two.
• Why the lid is wrapped in a cloth. A cloth under the lid is the first fix steaming gives for condensation. Here the drips do not only make the top rice soggy; they run down through the rice and put water back at the bottom.
• The cone and the holes. The holes go down to near the bottom for the reason plov calls its chopstick holes steam channels, and the rice is heaped loosely into a cone rather than pressed so the steam has a way out.
• The boil is the chelow's. The rice under kabab koobideh is made the same way: "boil it in salted water to al dente, drain", then steamed. It stops at six or seven minutes because the steam finishes the rest, as it does when biryani drains at 70%.