Bathe duck in a spiced (nutmeg, allspice) and spicy (habanero) marinade, stick it in the oven, ignore it for five hours, then serve it with fixings for build-it-yourself tacos.
Not just for slaw, cabbage is a snappy base that can handle lots of refreshing acidity-in this case from torn grapefruit and hot-and-sour chiles-without withering.
Masa labeled "masa preparada para tamales" often contains baking powder and salt, so don't add either if it does. Soak the husks three hours ahead or overnight.