In the meantime, rinse pork shoulder and pat dry with paper towels. Place it in a large Ziploc bag or a sous vide bag.
Place all the ingredients for the chipotle sauce in a blender or food processor. Blend well. Pour the sauce over the pork. Shake gently until the sauce covers all sides of the pork.
If using a sous vide vacuum bag, seal with a vacuum sealer or a hand pump, then slowly lower it into the prepared water bath. If using a Ziploc bag, leave it open and slowly lower it into the prepared water bath using the displacement method to let the water push the air out, then zip it up. Make sure that the pork is completely under the water line.
Cover the sous vide container with plastic wrap to prevent the water from evaporating. Set timer for 24 hours.
Once the pork is done, transfer it to a cutting board, a large plate, or a baking sheet lined with foil. Shred the pork using two forks. Reserve the cooking juice.
For a crispy top, insert the baking sheet under a preheated broiler and broil for 7-10 minutes until the top side of the pork is golden-brown and crispy. You may also sear the pork in a hot cast iron skillet or a large nonstick pan, one layer at a time. No need to add any oil. (This step is optional but highly recommended.)
Mix the pork with chopped cilantro.
To assemble the lettuce wrap, place a generous amount of pork on one lettuce leaf, top with red onion and diced avocado. Drizzle with the cooking juice if desired. Repeat for more lettuce wraps. Enjoy!
For leftover pulled pork, place it back into the cooking juice and refrigerate. The juice will enhance the flavor even more the next day.