2tablespoonsfresh rosemaryminced, or substitute 1 teaspoon dried
1cedar planksoaked in water for 1 hour
Fill a medium pot fitted with a steaming basket with a few inches of water. Place over high heat and bring to a boil.
Scrub the potatoes and chop into 1/2" cubes, leaving the skin on if desired. Transfer to the steaming pot and cover.
Steam the potatoes for 10-15 minutes or until tender when poked with a fork.
Drain the potatoes in a colander. Empty the water from the pot and wipe dry. Return to the stove but turn off the burner.
Add the butter to the pot and let it start softening. Then add the potatoes.
Use a potato masher to mash the potatoes while adding the milk. Don't add all of the milk unless you need it. Add just enough to get them the consistency you are looking for. A thicker mashed potato will stay on the cedar plank. A thinner mashed potato will have a tendency to run off the plank, so aim for a thicker version.
Stir in the sour cream, garlic and rosemary.
Fire up your grill for indirect cooking at 350 F. Note: If you prefer, char the plank over direct heat first.
Mound the potatoes onto the plank and add the cheese and green onion. Grill for 20 minutes or until the cheese is melted and the potatoes are hot.
Note: If you are using refrigerated potatoes, heat them for 10 minutes on the plank without the cheese and green onion first. Then, add the cheese and onion and heat another 20 minutes.
I found these potatoes to be best when made the day before. Then, the next stay, just spoon them onto the plank, add the cheese and onion, and heat on the grill.