Preheat oven to 450F. Line a baking pan with parchment paper.
Bring a large pot of water to a boil. Add the peeled and chopped potatoes to cook until fork tender. Drain into a strainer, then let steam dry for 5-10 minutes.
Add the potatoes to a large bowl with a pinch of salt and the chopped sage. Toss vigorously to roughen up the edges for 30 seconds to 1 minute. Transfer to the prepared baking pan.
Drizzle generously with the olive oil.
Roast for 30-40 minutes, until crispy and deeply golden, tossing every 15 minutes.