Place the orange juice and lime juice in a gallon-sized zip-top bag.

Roughly chop the onion. Peel and smash the garlic cloves. Add to the bag.

Season the pork chops on both sides with salt and black pepper, and place them in the bag. Seal the bag, and shake to coat the meat. Transfer the bag to the refrigerator, and marinate for 1-2 hours (no longer).

Preheat the oven to 350°F.

Line a large baking sheet with parchment paper.

Remove the marinated pork chops from the refrigerator. Drain the pork chops from the marinade, shaking off any onion pieces, and place on the baking sheet.

Place the brown sugar, cumin, paprika, and cayenne in a small bowl. Stir with a fork to combine.

Rub each of the pork chops on both sides with an equal amount of the sugar and spice mixture.

Set a large skillet over medium-high heat and pour in the olive oil. Once the oil is shimmering, place two pork chops in the skillet. Sear the pork, undisturbed, until browned on the bottom, 1-2 minutes. Flip the chops and sear for an additional 2 minutes on the other side. Transfer the pork chops to the baking sheet.

Repeat the searing step with the remaining oil and pork chops.

Bake the pork chops on middle rack of oven until the meat reaches an internal temperature of 140°F, 9-11 minutes.

Check to see that pork chops are done. Remove from oven or add time as needed.

Allow the pork chops to rest for 3 minutes. Plate the pork chops and serve immediately, garnished with chopped cilantro and avocado slices, if desired.