Boil, steam or slow roast potatoes until they are tender (15 minutes).
Stabilize your grill to 350°F.
Using a 10 inch cast iron skillet, place bacon in the skillet and place in the grill then close the lid checking periodically, render bacon until browned. With tongs, transfer to a paper towel, let cool and crumble for later use.
Add shallots to the bacon grease and cook until tender, about 5 minutes. Remove from heat.
Make the dressing. In a large mixing bowl, whisk together the shallots, vinegar, sugar, mustard, salt and pepper.
Using a cast iron griddle, soap stone, or cast iron pan, add the cooked potatoes to the hot surface and top with the Goose or Duck Fat. Let the fat melt into the potatoes and season with a pinch of salt. Let stand for 2 minutes and using a spatula, scrape the surface and flip the potatoes, be sure to capture the crust!
After another 2 minutes of grilling the potatoes, transfer them straight hot off the grill to the bowl with the dressing. With a rubber spatula, gently stir. Allow the mixture to sit at room temp for 20 to 30 minutes. Stir occasionally and allow the potatoes to absorb the dressing.
Stir in the green onions and add the crumble the bacon on top. Enjoy!