Remove the stems and seeds from the dried chiles by cutting off the top stem and shaking it upside down so the seeds fall out. Discard the seeds.
Lightly toast the dry chiles in a medium/large enamel dutch oven over low-medium heat until fragrant. Toast on both sides careful not to burn the chiles, which will make them bitter.
Place chiles in a large bowl and cover with hot water. Place a small plate over top to weigh them down to submerge. Soak until soft, about 30 minutes,
Drain the chilis while reserving the water. Place the chiles in a blender or immersion blender cup and add the cumin, black pepper, salt, cayenne, smoked paprika, and ½ cup of reserved water. Puree the mixture to form a smooth paste, adding more water only if needed. Set aside.
Heat skillet to medium-high heat and lightly coat with avocado oil to smoking hot. Sear the meat (season with salt and pepper first) in batches to brown the top and bottom of the cubes. Do not overcrowd the pot, you will not get a good sear. Transfer beef into a bowl and reserve.
Reduce pot to medium heat and add the onion to cook until translucent, a few minutes. Add garlic and cook for another minute or so until fragrant. Add the chili paste in, stirring well to combine. Next, add the stock in.
If you prefer a smooth chili, you can use an immersion stick to blend the contents smooth at this point (optional).
Mix the corn starch with a small amount of cold water in a small bowl to remove any clumps. Gradually whisk the corn starch mixture into the pot.
Add beef into the pot, cover, and reduce to a low simmer for 1-2 hours.
Once the beef is tender, add in the vinegar, to taste.