Start by mixing the chili powder, cumin, oregano, smoked paprika, salt, and black pepper in a small bowl to create a spice rub.
Rub the spice mixture evenly over the chunks of pork shoulder, ensuring every piece is well-coated.
Place the quartered onion and minced garlic at the bottom of the slow cooker. This will infuse flavor into the pork as it cooks.
Add the seasoned pork on top of the onions and garlic in the slow cooker.
Pour the orange juice, lime juice, and chicken broth over the pork, ensuring it is mostly submerged in the liquid.
Cover the slow cooker and cook on low for 8 to 10 hours, or until the pork is fork-tender and easily shreds.
Once the cooking time is complete, carefully remove the pork from the slow cooker and place it on a large cutting board. Let it rest for a few minutes.
Using two forks, shred the pork into bite-sized pieces. Discard any excess fat and bones.
For added texture, heat the vegetable oil in a large skillet over medium-high heat. Once hot, add the shredded pork in a single layer and crisp it up for about 3-5 minutes, turning occasionally until golden brown.
Serve the crispy carnitas in warm tortillas or over rice, garnished with your favorite toppings such as cilantro, diced onions, or avocado.