Soak the chillies
Remove seeds and stems from your chillies, place them in a bowl, cover with just-boiled water and place a small plate on top of the chillies to keep them submerged.
Sear the meat
Put the casserole dish over medium-high heat with 1tbsp of oil, when hot, sear the meat on all sides until browned. Remove meat to rest on a plate. If you prefer, season the meat with salt before searing.
Make the sauce
In the same pot as you seared the meat, add more oil if necessary and fry the onion and garlic together until soft.
Then add the chopped tomatoes, cook for another 2 minutes. Add the soaked chillies, Mexican oregano, cumin, peppercorns, cloves, avocado leaves, cinnamon stick salt and apple cider vinegar with 2 cups of water. Cook on medium-low heat for 30 minutes. Cover the pot with a lid.
Remove avocado leaves and the cinnamon stick.
Blend until super-smooth, then strain through a medium meshed sieve into a bowl.
Cook the meat
Place the seared meat in the slow cooker. Pour the sauce and 2-3 cups of water, so the meat is all covered. Cook on high heat for 6 hours, or until the meat is easy to shred.
Once ready, remove the meat to a bowl and shred with two forks. Season the broth with salt if needed. Mix your shredded meat with a cup of broth. Keep the rest of the broth reserve warm.
Make Quesabirrias
Heat up a non-stick pan on medium heat, dip a tortilla into the top of the broth and fry for 30 seconds. Flip, add a generous amount of shredded meat and grated cheese. Fold to make a quesadilla and fry from both sides.
When the cheese has melted and the outside looks toasted, garnish with Habanero Hot Sauce, onion, and coriander.
Serve with a small bowl of broth on the side to dip your quesabirria in.