How to Make It
Wash the rice thoroughly. Transfer it to a large bowl and add 3 tablespoons salt and enough water to cover by 2 inches. Let soak for 2 to 3 hours. Drain well.
In a large heavy saucepan, bring 4 quarts of water to a vigorous boil. Add 1 tablespoon salt and gradually sprinkle in the rice. Stir gently and bring back to a boil. Boil the grains just until tender outside but still slightly resistant at the core, about 4 minutes. Drain the rice in a sieve and rinse under tepid water to cool.
Return the saucepan to high heat and add the oil. In a bowl, whisk the yogurt and egg together, then stir in 2/3 cup of the rice. Carefully spread the mixture evenly over the bottom of the pan in the sizzling oil. Gradually sprinkle the rest of the rice into the pan in a mound. Poke 4 deep holes in the rice.
Cover the saucepan with a lid wrapped in a tea towel and cook over moderately high heat until steam builds up, about 1 minute. Reduce the heat to moderately low and cook for 30 minutes; the rice is done when the grains are tender and fluffy. Set the saucepan in 1 inch of cold water for 1 minute.
Scoop 1/2 cup of the cooked rice into a bowl and toss with the dissolved saffron. Mound the rest of the rice on a platter. Top with the saffron rice. Scrape the crust from the bottom of the pan, arrange it on the rice and serve.