In a large pot of salted water, boil the potatoes until they are just about fork tender. Do not overcook. Drain the potatoes and cool. Slice the potatoes about 1/4-inch thick.
In a large, heavy-sided cast iron skillet, add the shortening, onions, and potatoes and cook over medium heat until golden brown. Season with salt and pepper, to taste.
Professional Recipe: This recipe was provided by a chef, restaurant or culinary professional and makes a large quantity. The Food Network Kitchens chefs have not tested this recipe in the proportions indicated and therefore cannot make any representation as to the results.