6 tablespoons (54g) Diamond Crystal kosher salt, divided, plus more as needed; for table salt, use half as much by volume or the same weight
3 tablespoons (42g) unsalted butter (see notes)
2 generous pinches ground saffron (optional)
In a large bowl, cover rice with enough cold water to cover by 1 inch. Using your hand, swirl the rice around until the water turns cloudy. Pour off the cloudy water through a fine-mesh strainer, then return rice to bowl and refill with fresh cold water. Repeat the process until the water runs clear, about 5 or 6 times. Drain the washed rice well in the colander. Return drained rice to large bowl along with 3 tablespoons (27g) salt. Add enough cold tap water to cover the rice by 1 inch. Gently stir to dissolve the salt. Let stand at room temperature for 2 hours. Drain in the small-hole colander. In a large pot or Dutch oven, bring 2 quarts (1.9L) water to a rolling boil over high heat. Add 3 tablespoons (27g) salt. Add drained rice, then gently stir to ensure that there is no clumped rice and there is no rice stuck to the bottom of the pot. Return to a vigorous boil, then cook until the the rice has grown 1.5 to 2 times in length and the outside of each grain is cooked but not mushy and the center of the grain shows some resistance, 5 to 8 minutes. Immediately remove from heat and drain through a small-hole colander. Rinse rice well with cold water for about 30 seconds (you want to stop the cooking and to wash off any excess starch released during boiling). Taste a few grains of rice for saltiness; if more seasoning is desired, sprinkle rice all over with 1 teaspoon salt. In a small pot, combine butter with 1/3 cup (80ml) water and heat just until butter is melted. If using saffron, in a very small bowl, steep ground saffron in two tablespoons of hot water; set aside. Wash the pot used to parboil the rice. Pour half of the water and butter mixture into the pot. Using a large spoon or a spatula, gently mound the parboiled rice into the center of the bottom of the pot; do not dump the rice from the colander. Instead, carefully build the mound up, making sure the rice forms a mountain shape and does not touch the sides of the pot. Using the handle of a wooden spoon, make 6 to 8 holes deep into the mound including one in the center (this will facilitate the release of steam from the lower parts of the mound). Wrap the pot’s lid in a clean, thick kitchen towel, then cover the pot tightly (wrapping the lid in a kitchen towel prevents steam from escaping and absorbs any moisture that would have condensed on the inside of the lid and dripped down on the rice). Set over medium-high heat and cook until you can hear sizzling sounds inside the pot and steam begins to fill it (you can carefully lift the lid to peak if unsure), about 5 minutes. Uncover pot, gently pour the remaining water-butter mixture over the rice mound, then re-cover pot with the towel-wrapped lid. Reduce heat to medium-low and cook until rice is tender and fluffy, about 45 minutes. Using a slotted spoon or a spatula, and starting from the top of the mound of rice in the pot, gently spoon the rice onto the center of a serving platter to form a mound. After each spoonful, fluff the rice in the pot before transferring the next spoonful. Continue until you reach the near bottom of the pot where you may find a crunchy layer of rice (the crunchy layer of rice at the bottom of the pot is a Persian delicacy called tahdig; scrape it off—it may or may not come out in one piece—and serve it on a separate small plate to be shared among the diners). If using saffron, add 2 or 3 heaping tablespoons of cooked rice to the prepared saffron water and stir to evenly coat. Sprinkle the golden yellow grains of saffroned rice garnish on top of the mound of rice in the serving platter. Serve.