Preparation

Make the mojo

• Combine the garlic, salt, pepper, and oregano in a food processor and pulse until finely chopped. Transfer to a medium bowl and whisk in the juices. Reserve 1/2 cup of the mojo and refrigerate until ready to serve.

Marinate and grill the pork

• Use a paring knife to make 20 deep slits all over the pork. Using your fingers, push the remaining mojo into the slits. Wrap the pork well in plastic wrap, place skin side up on a rimmed baking sheet or platter, and refrigerate for at least 8 hours.
• Let the pork sit at room temperature for 1 hour before cooking. Meanwhile, set up a charcoal or gas grill for indirect cooking between 325°F and 350°F; if using a charcoal grill, bank the lit, ashed-over coals to one side of the grill. Cover the grill, and adjust the vents as needed to reach the temperature range. For a gas grill, cover the grill, turn off one or more of the burners, and adjust the active burner(s) to reach the temperature range.
• Pat the pork skin dry with paper towels. Put the pork, skin side up, on the cooler part of the grill and cook, rotating (but not flipping) every couple of hours, until the skin is crisp and an instant-read thermometer registers 190°F to 200°F in the center of the pork, 6 to 8 hours.
• Toward the end of the pork’s cooking, combine the reserved 1/2 cup mojo, the onion, olive oil, and lemon juice in a 2-quart saucepan. Cook, stirring often, over medium-low heat, until the onion softens and the flavors meld, about 8 minutes. (The mojo can sit at room temperature for a few hours.)

Serve the pork

• Transfer the pork to a cutting board. Remove the skin. Tent just the pork with foil and let sit for up to an hour before serving. Scrape off and discard the soft fat underneath the skin, then cut the crispy part (the crackling) into bite-size pieces. Transfer to a small platter, add a few lemon wedges, and serve the chicharrones (cracklings) as an appetizer.
• Meanwhile, use your hands to break the meat into chunks and transfer to a large bowl. Pour about 1/3 cup of the mojo over it and toss to coat. Transfer to a large platter along with the remaining lemon wedges. Sprinkle with the sea salt and serve, passing the remaining mojo around the table with it.

Make Ahead Tips

Once prepared with the mojo, the pork can be refrigerated for up to 24 hours before grilling.