Add raw potato cubes to a large saucepan; pour in just enough water to cover them. Add a generous pinch of salt. Bring to boil over medium-high heat. Reduce heat slightly and simmer for 7-9 minutes, until potatoes are tender on the outside, but still firm in the center. With the lid, carefully strain out the water.
Cover saucepan with lid and, with potholders on each hand, grip the sides of the saucepan, securing the lid. Shake vigorously. Check to see if the potatoes look fuzzy. If not, shake again.
Add olive oil to a large, hot cast iron skillet set over medium heat. Add potatoes; with a spatula, gently spread into a single layer. Without stirring, allow potatoes to crisp on one side. Once crisp, turn with spatula and again spread into a single layer to crisp. Repeat process until potatoes are crisp on all sides, 15 to 20 minutes total.
Remove potatoes from heat and season to taste with kosher salt. Serve.