Slice potatoes in half.
Place potatoes, rosemary, garlic, and peppercorns in a large saucepan.
Cover with water.
Add salt.
Bring to a boil over high heat.
Reduce heat to medium and cook for 5 minutes.
Turn off heat.
Let potatoes stand in brine for at least 5-6 hours.
When ready to cook, heat the oven to 425 °F.
Spray a sheet pan with cooking spray. Set aside.
Drain potatoes.
Remove rosemary, garlic, and peppercorns.
Place potatoes in a bowl.
Add olive oil.
Toss potatoes to coat.
Pour onto prepared sheet pan.
Roast, stirring occasionally, for 20-25 minutes, until golden brown and crisp.
Serve immediately.