Prep the garlic by smashing the cloves with the side of a knife and peeling them.
In a bowl or jar, whisk together orange juice, lime juice, cumin, chili powder, oregano, salt, and chipotle powder until combined.
Arrange the chicken thighs in the bottom of the Instant Pot or slow cooker. Tuck the smashed garlic among the pieces and pour the citrus-spice mixture over the top.
Prepare any toppings now (chop cilantro, slice avocado and jalapeños, wash lettuce or warm tortillas) so you can finish and serve right away.
Cooking
For the Instant Pot: Lock the lid and set to HIGH pressure for 12 minutes (for thighs) with a natural release of 10 minutes. Drain and discard excess liquid or reserve 1/4 cup for extra moistness.
For the slow cooker: Cook on LOW for 4–6 hours or HIGH for 2–3 hours, until the chicken shreds easily with forks.
Crisping
Preheat your broiler and spread shredded chicken on a rimmed baking sheet in an even layer. Broil 4–6 inches from the heat for 5–8 minutes, watching closely until edges are dark and crisp.
Alternatively, heat 1–2 tablespoons oil in a hot skillet and sear batches until caramelized.
Serving
Serve these carnitas in a variety of ways: in lettuce cups, warm tortillas, over rice, or loaded nachos.
Notes
Fresh citrus brightens the flavor — bottled juice won’t deliver the same brightness. Refrigerate leftovers up to 4 days or freeze for up to 3 months. Reheat gently to retain crispiness.