Step 1

Scrub potatoes and place in a medium saucepan. Add cold water to completely cover potatoes. Bring water to a boil over medium-high heat, add 1 tablespoon kosher salt, reduce heat to a simmer. Cook potatoes until a pairing knife can be slide into center of potato with no resistance, about 20 minutes. Strain potatoes and let sit until cool enough to handle.

Step 2

Arrange potatoes on a baking sheet. Gently smash each potato with the palm of your hand until split open, but not breaking apart. Brush potatoes with olive oil and season to taste with salt, pepper, and half of the rosemary. Flip potatoes, oil and season second side.

Step 3

Light one chimney full of charcoal. When all the charcoal is lit and covered with gray ash, pour out and spread the coals evenly over entire surface of coal grate. Set cooking grate in place, cover grill and allow to preheat for 5 minutes. Clean and oil the grilling grate. Place potatoes on grill and cook until lightly browned and crisped, about 5 minutes per side. Remove potatoes to a platter, sprinkle with remaining rosemary to taste, and serve immediately.