My wife has quite the international background, and while she was born in China, she actually spent the majority of her childhood in Panama before moving to the US as a young teenager. While growing up in Panama, she and her family had a maid that would cook meals for them. One of my wife's favorite dishes was carnitas, and she said the maid would cook it in a pressure cooker.
Pressure cooking is gaining more popularity nowadays and it's featured as a cooking technique in the Modernist Cuisine cookbook, but pressure cooking actually is really old school. There's evidence that pressure cooking was invented and used as early as the 1600s.
I had never actually seen a pressure cooker until watching an episode of Iron Chef on the Food Network. On Iron Chef, contestants have an hour to cook the secret ingredient, which in this case was beef chuck, a tough cut of beef that typically requires long amounts of cooking to become edible. The Iron Chef used a number of pressure cookers to quickly breakdown and tenderize the secret ingredient. That sparked my interest in pressure cookers - if an Iron Chef used them, why shouldn't I?
If you aren't familiar with pressure cookers, here's the skinny on how they work. In an ordinary non-pressurised cooking pot, the boiling point of water is 212 °F. However, in a sealed pressure cooker, the boiling point of water can increase to a much higher temperature because of the pressure that builds up in the pot due to the steam trapped inside. This higher temperature water and vapor transfers heat very rapidly to the food, dramatically shortening the cooking process.
For a party we recently attended, we made some carnitas using the recipe my wife's family maid followed years ago. It's actually really easy and doesn't take much time at all using a pressure cooker.
We went to our local grocery store and purchased some pork shoulder - it's a pretty inexpensive cut of meat that shouldn't cost more than a couple dollars per pound.
We cut this into a few large chunks and seasoned them liberally with a combination of salt, pepper, garlic powder, onion powder, and oregano. We then browned the meat in the bottom of the pressure cooker pot.
After browning the meat, we threw in some roughly chopped celery, green bell pepper, onions and garlic and let these aromatics sweat down a bit. After a few minutes, we then added water - yep, plain water - enough to just cover the meat and vegetables.
We brought this up to a boil, sealed the lid on the pressure cooker, and let it rip for about an hour. Here's the final result:
The carnitas are great and about as good as you would find at any local Mexican restaurant. We typically eat this as tacos with some store-bought corn tortillas and a quick homemade pico-de-gallo.