Bring water and salt to a boil in a large stockpot over high heat. Meanwhile, place rice in a colander and rinse with cold water until water runs clear, about 1 minute.

Add rinsed rice to boiling water. Reduce heat to medium. Cook, stirring occasionally, until rice is almost tender, about 6 to 8 minutes. Drain rice and immediately rinse with cold water until rice is room temperature, about 1 minutes.

Place 1 cup cooked rice in a medium bowl with sour cream; stir to combine. Heat 2 tablespoons butter and oil in a well-seasoned 10-inch cast iron or nonstick skillet over medium-low heat until just melted. Spread rice and sour cream mixture in an even layer in bottom of skillet.  Spoon remaining cooled rice on top, being sure to mound rice slightly towards the center, while still allowing rice to touch edges of skillet. Using the handle of a wooden spoon, poke 6 to 7 holes in the rice, going all the way to the bottom of the skillet to allow steam to escape. Cook 15 minutes, turning skillet on burner a quarter turn every 3 to 4 minutes to ensure even browning.

Cut remaining butter into small cubes. Add butter cubes around edges of rice and in steam holes after 15 minutes of cooking. Continue to cook over medium-low and turn skillet a quarter turn every 3 to 4 minutes until bottom and sides of rice are golden and crisp, another 15 to 18 minutes.

Remove from heat and cover skillet with a large plate or serving platter (right side down). Carefully but swiftly (and with confidence!) invert rice in skillet onto serving plate. Serve warm.