Rice from Iran or Basmati rice
A heavy pot with a tight fitting lid – Le Creuset dutch ovens are ideal
A wooden spoon with a long thin round handle
A tea towel
First, rinse basmati rice until water runs clear and soak for at least 30 min. Drain into a wire mesh strainer and rinse again. 2 cups is a reasonable amount for 4-6 people, keeping in mind that Persians like to see a generous portion of rice for guests and might make much more.
Meanwhile, soak some saffron–as much as half a gram–in a little boiling water, maybe 30ml half a gram. Soak as much as you can, because the aroma is important to the finished dish. The water should turn ruby red. You can store leftover saffron water in a jar in the fridge for a couple of days or use it in other dishes to go with the rice.
Boil lots of salted water, say 5qt for 2 cups soaked rice. Add the soaked rice and parboil until rice is partially cooked but still firm. Strain and set aside to drain.
To get the crust (tahdig):
Start with butter. Unless you are keeping kosher or have health concerns, there will be NO oil of any type in this rice. (Margarine is too vile to be mentioned in this context.) For a Le Creuset type round dutch oven, start with 2-3 tablespoons on the bottom of the pot.
Now, you can have a rice crust, a potato crust, or a bread crust.
It’s hard to pull off a plain rice crust without making it too brittle, but this is how it is done: mix egg yolks or yogurt mixed with saffron water with enough rice to thinly cover the bottom of the pot. Or just mix rice with a lot more butter.
For a potato crust, thinly slice (quarter inch) 1-2 peeled potatoes. Arrange in slightly overlapping circles in the melted butter at the bottom of the pan. Don’t make the potato slices too thin or they might burn before the rice is done steaming.
For a bread crust, take thin slices of crustless white bread and arrange the same way as for the potatoes.
Now mound the drained rice over the crust you’ve prepared. Use the handle of a wooden spoon to poke holes in the rice and slip a few pats of butter in.
Finally, drizzle some saffron water over the top of the rice.
Now, take a folded tea towel (paper towels will work in a pinch) and stretch taut over the rim of the pot, holding in place with the lid. The towel should trap the steam and keep it from condensing and running back into the pot.
Cook over very very low heat to steam the rice and brown the crust. After half an hour, you can crack the lid and start testing.
Serve by mounding the rice in a serving dish. Pry the crust up and break it into pieces. You can arrange these on the rice serving dish or use a separate dish. Sometimes the crust is served in a separate dish with some brothy stew over it (khoresht – like ghormeh sabzi or gheimeh), particularly if it is a very hard rice crust.