Step 1

Trim any excess surface fat from the pork and discard. Cut the pork into two pieces if needed to fit in a 6-quart or larger slow cooker. Sprinkle evenly with the salt, cumin, pepper, oregano, cinnamon, and cayenne if using. Place in the slow cooker.

Step 2

Place the garlic and chipotles around the pork. Pour the diced tomatoes and their juices and the liquid around the pork. Cover and cook until the pork is fork tender or falling off the bone, about 8 hours on the LOW setting.

Step 3

Using tongs, transfer the pork to a rimmed baking sheet (lined with aluminum foil if broiling). Remove and discard the bone if needed and any large chunks of fat, then use 2 forks to shred the meat into large chunks. The pork can be served at this point or browned in the broiler.

Step 4

If broiling, arrange a rack about 6 inches from the broiler and heat the broiler to high. Broil the carnitas until a dark golden-brown crust forms on top, 4 to 5 minutes. Flip the carnitas and broil until the second side is golden-brown, about 4 minutes more. Meanwhile, warm the tortillas one at a time over a gas burner, or stack and wrap completely in aluminum foil and warm in the oven while the carnitas is browning.

Step 5

Transfer the pork to a serving bowl. For carnitas tacos, serve in tortillas with accompaniments, like sour cream, cilantro, radishes, pineapple, chopped red onion, and lime wedges. If desired, skim the fat from the leftover juices and keep as a medium for moistening the carnitas when reheating.