Prepare the Chilies: Start by cleaning the chilies. Use a damp kitchen towel to wipe them down, then remove the stems and seeds. Place the cleaned chilies in a large bowl and cover them with hot water. Let them soak for about 10 minutes.
Blend the Sauce: After soaking, drain the chilies and put them in a blender. Add the garlic, oregano, cumin seeds, black peppercorns, bay leaf, and the pineapple juice. Pour in ½ cup of water and blend everything until you have a smooth sauce.
Marinate the Pork: Place the cubed pork in a bowl and pour the sauce over it. Mix well to coat all the meat. Cover the bowl with plastic wrap and let it marinate in the fridge for at least 2 hours, or overnight if you have time. This step makes the flavors pop!
Cook the Meat: In a large pan, heat the olive oil over medium-high heat. Add the marinated pork and cook it for about 5 minutes. Then, toss in the sliced onion and continue to cook, stirring constantly, for about 15 minutes or until the pork is cooked through and tender.
Add Pineapple: Stir in the diced pineapple and cook for another 30 seconds. Once done, turn off the heat and set the mixture aside.