Prepare a grill fire to about 350° with pecan chunks to add smoke flavor.

Scrub sweet potatoes and dry well. 

Place two chop sticks or skewers on a cutting board and place the sweet potato between them. They will be a guide to keep you from cutting all the way through the potato so that the slices will stay together to create the hasselback sweet potato.

Use a sharp knife, cutting into 1/8 inch slices, not cutting all the way through the bottom, so that the sweet potato remains in one piece and the slices fan out.

Create a shallow foil pan with a rim for the sweet potatoes.

Grill over indirect heat with the grill closed.

Cook sweet potatoes about 1 hour to one hour 15 minutes, depending on the size. 

Melt the butter and mix brown sugar with kosher salt.

Spoon melted butter over sweet potatoes, getting it down between the slices.

Sprinkle brown sugar and salt over each sweet potato. 

Continue to cook another 10- 15 minutes until sweet potatoes are tender when pierced with a fork or sharp knife. Spoon butter and brown sugar mixture from the tray over the sweet potatoes as they cook.

Remove from grill and place on a serving tray.

Pour remaining butter mixture over the sweet potatoes if desired and serve immediately.