Take pork out of the refrigerator and allow to sit at room temperature for 30 minutes.
In a small bowl, combine oregano, cumin, chili powder, salt and pepper.
Rub the spices over the entire pork butt.
Heat a cast iron skillet over medium heat.
Sear the pork on all sides, creating a deep browning on the outside of the meat.
Place the pork in the crockpot.
Deglaze the skillet with chicken broth, scraping the bottom to release any brown bits. Pour this broth into the crockpot over the top of the pork.
Add the diced onion, crushed garlic, diced jalapeño, and orange marmalade to the crockpot. Spread a little bit on top of the pork and drop a little bit on either side of the meat into the chicken broth.
Set the crock pot on low for 8 hours.
When pork is tender and falling apart, remove from the crockpot and shred onto a sheet pan. Remove any grisly or fatty pieces. Pour the broth from the crockpot over the shredded pork.
Turn broiler on high and broil for about 4 minutes, or until parts of the meat is crisping. Stir on the sheet pan and broil again to get even more crispiness.