Melt the tallow or lard in a large pan over medium-high heat either in the Instant Pot or in a separate skillet. Briefly fry the chiles until fragrant, about 10 seconds on each side. Remove the chiles to a blender or food processor (leaving the seasoned fat in the pan), cover with the very hot water, and let steep while you sear the meat. (Use a spoon or tongs to push the chiles down into the hot water if they’re not completely submerged.)
Season the beef with two teaspoons each salt and pepper. Sear the meat in the leftover chile oil over medium-high heat until well-browned, about 6 minutes total. (You may have to work in batches, depending on the size of your pan.) When all of the meat is browned, add it to the Instant Pot if you used a separate skillet up to this point.
Add the stock or water to the pan and use a metal spatula or a wooden spoon to scrape the browned bits off the pan. Add this liquid to the Instant Pot.
Add the garlic and onion to the blender and blend until nearly smooth. I wanted to strain the chile becasue sometimes there's skin left so I placed a strainer over the Instant Pot and poured the chili paste into the strainer and pressed with a back of a spoon, scraping the bottom of the strainer occasionally until there's nothing left in the strainer but the skin residue. Discard the residue.
Add the crushed tomato, 1 teaspoon salt, 1 teaspoon pepper, paprika, cumin, dried oregano, and cayenne (if using) to the Instant Pot. Seal the lid and run the high pressure setting for 40 minutes. Manually release the pressure.
Carefully open the Instant Pot and scoop out about a cup of the chili’s liquid into a heat-safe bowl. Whisk in the masa harina and add this mixture back into the Instant Pot. Stir to combine; the chili should thicken slightly.
Serve with whatever chili accompaniments you like best. I listed several we like in the body of this post!
