Place the onion, garlic and jalapeño in a single layer on a baking sheet. Move your oven rack to the top position and turn the broiler on. Place the baking sheet in the oven and broil until the tops of the onion, garlic and jalapeño are black. Flip them over and broil until the other side is charred as well.
Meanwhile, add the vegetable oil to a heavy bottomed pot that's just wide enough to accommodate the pork shoulder. Heat on high until the oil is shimmering. Add the pork shoulder and press it down to ensure there's good contact between the meat and the pot. Let this fry undisturbed until the bottom is nice and brown (about 5-7 minutes). Flip the pork over and brown the other side.
Once both sides of the pork are browned, add the charred onion, garlic and jalapeño. Wipe 1 Pasilla chili and 1 Guajillo chili and add them to the pot as well as the carrot, bay leaves, cinnamon stick, cloves, Mexican oregano, ground coriander and salt. Pour enough water into the pot so that the pork is submerged by 1" (about 5 cups). Bring to a boil and skim off any scum that floats to the top.
Cover the pot with a lid and let it simmer over medium low heat until the pork falls apart when prodded with a fork (about 2-3 hours).
Transfer the pork to a bowl, then strain the braising liquid through a strainer and set the pork stock aside. We're going to use this for both the mole and the masa.
To make the mole sauce, wipe the remaining Guajillo and Pasilla chiles with a damp paper towel, then trim the tops off the of the chiles with a pair of scissors. Use the scissors to cut down the length of each chile so you can open it up. Remove the seeds and light colored membranes, and lay the chilies flat on a baking sheet.
Roast the chiles in a 350 degree oven for a few minutes until you can smell the sweet fragrance of the peppers. This brings out the flavor of the chiles, but be careful not to burn them as they will get bitter.
Put the roasted chiles in a bowl and cover with boiling water. Allow them to rehydrate for 10-15 minutes, then scoop the chiles out, discarding the soaking liquid.
Add 1 tablespoon of vegetable oil to a frying pan and add the minced onions and garlic. Fry over medium low heat until the onions are fully caramelized (about 40 minutes). Turn off the heat and allow the onions to cool.
Add the sesame seeds to the bowl of a food processor and process until they are finely ground. Add the drained chiles along with the canned tomatoes and caramelized onions and run the food processor until smooth.
With the food processor running add some reserved pork stock 1/4 cup at a time until the mixture is smooth and does not clump anymore, but it is still thick. (you shouldn't need more than 1 cup). Scrape down the sides of the bowl a few times with a spatula. Add the honey, salt, mexican oregano, ground cumin and ground coriander and continue to process until well incorporated.
Strain the sauce mixture through a fine mesh sieve or chinois, pressing down on the solids to extract as much sauce as you can.
Shred the pork with a fork. Measure out 1 cup of the sauce and set it aside (for the topping), then add the remaining sauce to the pork. Stir to combine.
Rehydrate the corn husks in warm water.
To make the masa, whisk together the masa harina, baking powder and salt in a large bowl. Add 3 cups of the reserved pork stock and mix together with clean hands to combine. Keep adding pork stock 1/4 cup at a time, until the mixture is about the consistency of cookie dough.
Put the Manteca in the bowl of an electric mixer fitted with a whisk attachment, then beat until light and fluffy (about 5 minutes), scraping down the sides of the bowl once ( it will go from translucent to white).
Turn down the speed of the mixer, then incorporate the masa a little bit at a time. A classic way to test if your masa is light enough is to drop a little ball into a glass of water. It should float on the surface.
To wrap the tamales, place 1 rehydrated corn husk with the narrow end pointed to the left. Use a spoon or spatula to spread a thin layer of masa all the way to the left, right and bottom edges of the husk, leaving about a quarter of the husk exposed along the top. This space prevents the husk from getting sandwiched in between layers of masa, making the tamales easier to unwrap.
Place some of the pork filling along the middle of the layer of masa you just laid down, but leave a gap to the left.
Fold the narrow end of the husk over the filling.
Finish by folding the bottom flap over the filling, and then folding the top flap over the bottom flap. If you've done this successfully you should have a nice rectangular package with 3 sides closed and one side open (with the filling exposed). Place the tamale with the flaps facing down on a baking sheet.
Once you've wrapped all the tamales, prepare a deep pot with a steamer insert by filling the pot with water until the waterline is just below the level of the steamer insert. Place the tamales in the steamer vertically, with the open end facing up.
Wet a kitchen towel, and cover the pot with the towel before covering it with the lid. This prevents condensation from forming on the lid, which will drip down and maker your tamales watery. Make sure to fold the bits of towel hanging out of the pot over the lid so they do not catch on fire.
Bring the pot to a boil, then turn down the heat so you can barely see a steady stream of steam escaping. Steam the tamales for 1 1/2 hours. Make sure you check the steamer periodically to make sure you don't run out of water.
To make the sauce for the tamales, put the tomatoes in the food processor and process until smooth. Strain the tomato puree through a fine mesh strainer into a small sauce pan. Add the reserved 1 cup of mole sauce to the tomato sauce. Cook the sauce over medium low heat until the sauce is thick and bubbly. You'll want to stir it frequently to keep it from burning.
To serve, unwrap your steamed tamales, leaving them on the husks. Cover with the sauce and serve.
These tamales will keep for about 1 week in the fridge, or for a few months in the freezer. You can re-steam or heat them in the microwave wrapped in a damp paper towel to warm them up.