Combine all the ingredients in a large bowl. Stick the cloves into the onion pieces so they're easy to remove later. Season generously with salt and pepper, toss to combine.

Transfer the mixture to a large vacuum bag or resealable plastic gallon bag and seal tightly, pressing all the air out to prevent it from floating.

Fill cooking basin with water, attach the sous vide, and set to 165°F.

Place vacuum sealed bag in the water bath so that it’s fully submerged. The water will evaporate as it cooks, so make sure there’s an extra 2-3″ of water above the bag, or add more water while it’s cooking. Loosely covering the top of the basin with aluminum foil will help any evaporated water return to the bath and reduce the amount of water loss during cooking.

Cook for 18-24 hours. The meat will be fully cooked by 12 hours and can be removed then, but at 18-24 hours the flavor and tenderness will be at its peak.

Remove the bag from the water bath. Transfer the pork to a large sheet pan, and transfer the aromatics and remaining juices to a small sauce pot.

Place the small sauce pot on the stove over medium-high heat and bring to a rolling boil to reduce.

Shred the meat using two forks or your hands, then place in the oven on the top rack under your broiler for 10 minutes, flipping and stirring the pieces halfway through. NOTE: If you don’t have a broiler, place the sheet pan on the top rack of your oven at 500°F degrees.

When the liquid in the pot has reduced by about half and the carnitas have come out of the oven, pour the liquid through a strainer into the sheet pan with the carnitas and toss to coat.