Trim only excess surface fat from the pork shoulder, leaving some fat attached for flavor and tenderness. Cut the pork into 2- to 3-inch chunks, then season thoroughly with kosher salt, cumin, oregano, and black pepper.

Add the onion, garlic, jalapeño, orange juice, optional orange zest, lime juice, and bay leaves to the slow cooker. Add up to 1/2 cup chicken broth or water if the cooker needs additional liquid, then arrange the seasoned pork over the aromatics.

Cover and cook on LOW for 8 to 10 hours or on HIGH for 4 to 5 hours. The pork is ready when it is very tender and pulls apart easily with a fork.

Transfer the pork to a bowl or baking sheet and shred it with two forks. Remove large pieces of fat, the onion pieces, and both bay leaves, while keeping the flavorful cooking liquid in the slow cooker.

Strain the cooking liquid and reserve it. Spread the shredded pork in a single layer on a foil-lined baking sheet, then spoon some of the strained liquid over the meat so it stays juicy during crisping.

Broil the pork 4 to 6 inches from the heat until the edges are browned and crisp, usually 3 to 5 minutes. Toss the pork, add a little more cooking liquid, and broil again for 2 to 4 minutes.

For skillet crisping, heat 1 to 2 tablespoons vegetable oil or reserved pork fat in a hot skillet. Crisp the shredded pork in batches for 8 to 12 minutes, turning occasionally and avoiding overcrowding.

Serve the hot carnitas in corn tortillas with cilantro, diced onion, lime wedges, salsa, avocado, or pickled onions. Pass extra strained cooking juices at the table for spooning over tacos, bowls, or rice.