Place the slow cooker on low and pour in the juices. Combine the taco seasoning, oregano, salt, cumin and pepper in a small bowl. Then rub onto the meat. Place pork into the slow cooker and then top with the onion and jalapeno. Cook on low for 8 to 10 hours or high for 5 to 6 hours, or until meat falls apart.
Remove meat from the slow cooker and onto a cutting board. Remove any excess fat and shred into smaller pieces. Remove any fat and the onions from the juices and then place meat back into the slow cooker. Stir the meat, so the juices are able to soak into the meat. Allow to sit for 5 minutes.
Turn on the broiler and set out a large baking sheet. Once oven has heated, place the meat onto the baking sheet and broil for 5 minutes. Remove from the oven and add a Tablespoon or two of the juices to the meat. Toss with tongs and then places back into the oven for another 3 to 5 minutes, or until the meat has reached your desired crispiness. Enjoy while hot!