One to three days before serving: Slit the chiles lengthwise and remove the seeds and veins. Tear them into flat pieces. Heat a heavy skillet or griddle pan over medium heat and add 1/4 cup of the lard. Toast the chiles for 1 or 2 minutes on each side, until toasty and slightly charred but not burned. Be very careful not to burn them or you will have to start again. Transfer the chiles to a bowl with a slotted spoon and cover them with warm water. Leave to soak overnight.
In a large bowl, combine the roasted tomatoes, breaking them up, and the chocolate, also broken up. In a mortar and pestle or a coffee grinder reserved for grinding spices, pulverize the peppercorns, cloves, allspice berries, and cinnamon. Add them to the tomato mixture and set aside.
In a large heavy skillet, dry-toast the sesame seeds to a deep golden color, just 10 or 15 seconds. Add to the tomato mixture and repeat with the coriander seeds. Wipe the skillet which you used to toast the chiles and add the remaining 1/4 cup lard. Toast the almonds for about 4 minutes, stirring occasionally, until browned through. Transfer them to the tomato mixture with a slotted spoon and repeat with the raisins, and then with the onions and garlic, pressing down on the ingredients with the back of the spoon to rid them of excess fat before transferring them to the bowl. If necessary, add a little more lard or oil to the pan and fry the tortillas until golden. Break them up and add them to the bowl, then brown the bread on both sides, tear into large pieces and add to the bowl. Stir the mixture together thoroughly, then place 1/4 of it in a blender jar with 1/2 cup of broth. Blend as smooth as possible, scraping down the blender jar. It is best not to add any additional liquid to the mixture; try to get it to move through the blades by pulsing on and off and scraping down the sides. Repeat with the remaining mixture, 1/4 at a time, adding 1/2 cup of broth to each batch. Strain the mixture through a medium-mesh sieve into a clean bowl and set aside.
Now puree the drained chiles in the blender with about 1/2 cup of their soaking water, in 3 batches (no need to wash the blender). Add a little more water if needed, and add the canned chipotle chile to the last batch. Strain the chile puree through the same sieve into a separate bowl.
In a very large (at least 8 quarts), heavy covered casserole, heat 1/4 cup of the lard over medium-high heat. Add the turkey pieces and brown, in several batches, for about 4 minutes on each side. Remove to a roasting pan and set aside. Pour off the excess fat from the casserole, leaving just a little on the bottom, and return to the heat for a moment to heat up. Add the chile puree to the casserole and cook, scraping the bottom of the pan occasionally, for about 5 minutes. The mixture should be quite dark and thick. Add the other puree and cook for a few more minutes, until it thickens once again. Add 5 cups of the broth, partially cover the pan and cook for 45 minutes over low heat, stirring occasionally. Add the salt and the sugar and, if the sauce is thicker than heavy cream, thin it with a little more broth.
Preheat the oven to 350 degrees and pour the sauce over the turkey. Cover the pan and roast until the pieces are tender with no trace of pink remaining, about 2 hours. Remove the pan from the oven and spoon the fat off the top or, if serving the following day, ideally let the dish cool to room temperature and refrigerate so the fat will congeal, making it easier to remove. Skin the turkey and cut the meat from the bones, or serve the turkey in large pieces, as desired. Reheat in a 350 degree oven for 15 to 20 minutes if needed, spooning some sauce over the top of the turkey pieces to give them a nice glaze. Scatter some sesame seeds over the top just before serving.
This recipe yields 6 to 8 servings.