Prepare cornhusks: Simmer the husks in water to cover for 10 minutes, weighting them with a plate to keep them submerged. Let them stand for a couple of hours until husks are pliable.
To make the dough: Beat the lard in a mixer until very light, for about a minute. Add 1/2 pound (1 cup) fresh masa to lard. Beat until well blended. Continue beating, adding alternately the remaining 1/2 pound masa and the poultry broth, adding only enough broth to give consistency of medium-thick cake batter. Then sprinkle in the baking powder and salt. Beat 1 minute more.
To make the salsa: Husk and wash the tomatillos. Put the tomatillos and 3 Serrano chiles and some salt in a pot of water and boil them until tender, about 10 to 15 minutes. Then drain them and put them in the bowl of a food processor. Add the coriander, onion, and garlic. Process until smooth. Heat 1 tablespoon lard in a medium large skillet over medium-high heat. When the lard is hot enough to make a drop of the tomatillo puree sizzle, pour it all in at once. Stir the sauce constantly for 4 to 5 minutes until it gets darker and thicker...thick enough to coat a spoon. Add the chopped tomatillos and cilantro. Season with salt. Mix the shredded chicken with 1/2 cup cooked tomatillo sauce.
To form the tamales: Remove husks from water when they have softened. Pat husks dry. Tear extra husks into 1/4-inch wide, 7-inch long strips -- one for each tamale. Take one that is at least 6 inches across on wider end and 6 to 7 inches long. Lay out this cornhusk with tapering end toward you.
Spread a couple of tablespoons of dough mixture into a square, leaving at least a 1 1/2-inch border on side toward you and 3/4-inch border along other sides. Pick up two long sides of cornhusk and bring them together, overlapping one over the other. Fold up the bottom section of husk tightly right up to the filling line. Leave top open. Secure it in place by loosely tying one of strips of husk around tamale. Repeat with remaining husks and dough mixture.
Stand tamales on the folded bottom in prepared steamer, being sure they are not packed too closely in steamer -- they need to expand. Cover with layer of leftover husks. Cover with lid and steam for 1 hour. Check carefully that all the water doesn't boil away, adding boiling water when necessary. Serve with additional salsa on the side.