Prepare for the Instant Pot: Once the pork has marinated, remove it from the refrigerator and let it come to room temperature if you set it to marinate more than the 30 minutes.
Optional: If you would like to sear the sides on "Saute mode" you are more than welcome to do that.
Pressure cook: (Once the pork is seared, remove it from the Instant Pot and set it aside). If you skipped the sear step simply place the pork shoulder in the Instant pot and add 1 cup of water to the pot, along with any remaining marinade.
Seal and cook: Secure the lid on the Instant Pot, ensuring the valve is set to the "Sealing" position. Select the "Manual" or "Pressure Cook" setting and adjust the cooking time to 75 minutes (15 minutes per pound) on high pressure.
Natural release: Once the cooking time is complete, allow the pressure to release naturally for at least 15 minutes. Carefully turn the valve to "Venting" to release any remaining pressure.
Finish and serve: Once the pressure has fully released, carefully remove the lid from the Instant Pot. Transfer the pork shoulder to a serving platter and let it rest for a few minutes before shredding it with two forks. Serve the pernil with your favorite sides, such as rice and beans, tostones, pan sobao, or root vegetables.