To cure duck: Stir together water, coffee, kosher salt, brown sugar and curing salt in a container until solids are dissolved, about three minutes. Add the sorghum and stir until dissolved. Add ice and stir until cure is cold (ice may not melt completely, keeping liquid cold slows salt absorption). Add duck to cure and weigh down with a large plate (to keep submerged). Keep container covered with a lid or plastic wrap for six hours. Rinse duck and pat dry, then discard brine.

To cook duck: Place the duck skin side up on a cutting board. Using a sharp knife, score four (quarter-inch deep) cuts across the skin at a 45-degree angle. Sprinkle 1/4 teaspoon salt and 1/4 teaspoon pepper over the meat side of each duck breast. Heat a well-seasoned skillet or nonstick pan over high heat. When pan is hot, add duck breasts, skin side down, and cook for five minutes or until skin is brown and crispy. Flip and cook for two minutes. Transfer the duck breasts, skin side up, to a cookie sheet. Bake at 350° on the top rack of the oven for six minutes.

To make waffles: Put the cubed sweet potatoes in a steamer basket and place them in a large pot of simmering water that is no closer than 2 inches from the bottom of the steamer. Allow potatoes to steam for 20 minutes or until fork-tender. Mash the cooked potatoes and set aside.

In a large bowl, whisk together flour, baking powder and salt, then set aside. In another bowl, combine the sweet potatoes, milk, brown sugar, butter and grated orange rind. Stir the sweet potato mixture into the flour mixture and thoroughly combine. Beat the egg whites until stiff peaks form. Gradually fold the egg whites into batter a third at a time. The batter will be thick. Using a scoop, place two scoops of batter onto a preheated, oiled waffle iron and cook until lightly browned, about five to six minutes.