1/2 cup coarsely chopped garlic (from about 1 medium head)
Leaves from 8 to 10 stems fresh cilantro
1/4 cup fresh lemon juice (from 2 lemons)
1/4 cup fresh sour orange juice (from about 2 medium; may substitute a 50-50 blend of fresh lemon juice and fresh grapefruit juice)
1/4 cup packed fresh oregano leaves
1/4 cup water, or more as needed
3/4 cup extra-virgin olive oil
3/4 cup vegetable oil
3 tablespoons kosher salt
1 tablespoon dried oregano
2 teaspoons freshly ground black pepper
One 4-pound, bone-in pork shoulder
For the marinade: Combine the garlic, cilantro, citrus juices, oregano and water in a blender; puree to form a smooth, thick liquid. With the motor running, add the oils in a slow, steady stream until evenly incorporated.
For the pork: Combine the salt, oregano and pepper in a small bowl.
Rinse the pork with cold water and pat dry with paper towels. Use a sharp knife to cut the skin and/or fat cap on your pork shoulder in a crosshatch pattern, leaving about an inch of space between the cuts. Be sure to slice through the layer of fat below the skin, but not into the meat itself.
Rub the pork all over with the salt mixture, then place in a gallon-size zip-top bag. Add the marinade, pushing it into the nooks and crannies and pressing out as much air as possible, and seal. Refrigerate, turning occasionally, for 12 to 24 hours.
Let the pork sit at room temperature for 30 to 45 minutes while you preheat the oven to 350 degrees. Reserve the marinade.
Place the pork shoulder fat-cap side up in a Dutch oven or other large, heavy-bottomed pot with a tight-fitting lid. Add 3/4 cup of the marinade and the water. Cover and roast (middle rack) for 3 to 5 hours, until the meat is fork-tender. Use tongs or large forks to flip the roast every hour or so, and use some of the marinade mixture to baste the meat. Add a tablespoon of water or two if the pan is dry. Finish cooking for last hour with fat-cap side up.
To help crisp the fat cap on top of the pork and further brown the meat, uncover the pot and increase the oven temperature to 375 degrees. Roast for 10 to 15 minutes.
Place the meat in a large bowl or on a large cutting board with a channel that can catch the juices. Use two forks to shred the roast pork into bite-size pieces. Add 1/2 cup of the pan juices (or as much as you like), and stir to incorporate.
VARIATION: To make the pernil in an Instant Pot, ask the butcher to remove the bone from pork shoulder and cut the meat into four equal pieces; reserve the bone. Follow the marinating directions above.
Remove the shoulder from the marinade and shake dry; reserve the marinade.
Add 1 1/2 tablespoons extra-virgin olive oil to the Instant Pot. Set to SAUTE on high heat; add the hunks of meat and sear them on all sides, about 3 minutes per piece, in batches, then transfer them to a plate.
Add 1 cup of the reserved marinade to the Instant Pot. Use a wooden spoon to scrape away any blackened bits. Turn off the heat.
Arrange the hunks of pork around in the pot, then baste with the reserved marinade.
Add the bone, cover and cook at high pressure for 80 minutes. Let the pressure release naturally.
Transfer the meat to a cutting board. Cook the marinade over medium heat until slightly reduced; skim fat and season, as needed.
Add the pork and shred it with forks.
Crisp the pork under the broiler, if desired.