I start by whisking fresh orange and lime juices with garlic, cumin, oregano, red pepper flakes, salt, pepper, and olive oil. This bright, tangy marinade is what makes the pork so flavorful.
Cut pork shoulder into chunks and sear in a skillet until browned on all sides. Searing locks in moisture and enhances flavor before it hits the slow cooker.
Place seared pork in the slow cooker, add marinade and bay leaves, and cook on LOW for 8 hours or HIGH for 4 hours. The pork should shred easily with a fork.
Slice the bread, spread mustard, layer Swiss cheese, ham, shredded pork, and pickles. Top with more cheese, then the second half of the bread.
Melt butter with garlic powder and brush on the outside of the bread. Press sandwiches in a hot skillet with a heavy pan until golden brown and melty.