Place 1 cup basmati rice in a fine-mesh sieve or bowl and rinse under cold running water, swirling gently until water runs clear.
(Optional) Soak the rinsed rice in fresh cold water for 20–30 minutes, then drain thoroughly.
Transfer the drained rice to a medium saucepan with a tight-fitting lid. Add 1½ cups cold water, ½ teaspoon salt, and 1 teaspoon unsalted butter or neutral oil. Stir gently to combine.
Place the saucepan over medium-high heat and bring to a rolling boil.
As soon as it boils, reduce heat to the lowest setting. Cover tightly and simmer undisturbed for 15 minutes.
Remove the pan from heat, keep it covered, and let the rice rest for 10 minutes.
Remove the lid and gently fluff the rice with a fork. Serve immediately.