Heat a small skillet over medium-low heat. Add the duck breast skin side down and cook for 15 to 20 minutes, until the skin side is lightly browned and the fat is rendering. Sprinkle the duck with the mustard seeds and flip with a metal spatula.
Cook for another 3 minutes, until seared on the meat side but still
While the duck rests, in a medium saucepan, combine the reserved 2 tablespoons duck fat with the maple syrup, scallions, corn, and minced chile and bring to a simmer over low heat.
Reduce the heat and simmer for 15 minutes, until the syrup is infused with the flavors of the scallions, corn and chile.
Thinly slice the duck breast against the grain, sprinkle with the chili powder, season to taste with salt and pepper. Divide the slices between 2 plates, fanning them in an attractive pattern. Drizzle the Corn-Chile Maple Sauce over the slices. Season the toasted panko with salt and pepper and scatter over the duck.