In an 8-inch cast-iron frying pan over medium heat, cook tomato pieces and marjoram or oregano with no oil until condensed, 10 to 15 minutes. First they will give off their juices, then they will dry out. Puree the tomato mixture in a blender then pass the mixture through a sieve or food mill.
In a medium frying pan, heat 2 tablespoons of the oil over medium heat and fry the plantain and bread slices until brown, about 12 minutes. Remove from the pan. Add more oil (if needed) and fry the raisins until they are plump, about 3 minutes. Remove them from the pan. Fry the almonds until light brown, about 4 minutes. Remove from the pan. Place the plantain, bolillo, raisins, and almonds in a blender with 1-1/2 cups of the reserved broth and blend until smooth. Wipe out the frying pan and put over low heat. Add 1 teaspoon of oil and the sesame seeds and fry until brown, about 10 minutes, stirring constantly. Cool the seeds and grind in a molcajete or spice grinder.
In a heavy 6-quart stockpot, heat 1 tablespoon of lard over high heat until smoking. Add the chile puree a little at a time, stirring constantly. It will splatter about a bit, but keep stirring. Lower heat to medium and after about 20 minutes, or when chile puree is thick, add the tomato mixture and continue to cook, about 15 minutes, stirring to keep the mole from sticking or burning. Add the onion and ground spice mixture and stir well. Add the pureed plantain mixture and ground sesame seeds, stirring constantly, about 10 minutes. Add 4-1/2 to 5 cups of the reserved broth to thin the sauce, then add the chocolate, stirring constantly. When the chocolate dissolves, add the salt. Let it cook down for 30 minutes, stirring occasionally. The more time it has to cook, the better.
Return the chicken pieces to the broth and heat through. Add more broth to the mole if needed. The mole should be thick enough to just coat a spoon, no more. Place a piece of chicken on a serving plate and ladle a large spoonful of mole on top. It should completely cover the meat. Serve with corn tortillas.
Hint: You can use turkey or pork instead of chicken. If you want to make it less picante, use half the amount of chiles and the same amount of the other ingredients.
Adapted from Seasons of My Heart: A Culinary Journey Through Oaxaca by Susana Trilling (Ballantine Books, 1999). Copyright 1999 by Susana Trilling.