For marinade:
Slice onions and garlic and add to large bowl.
Add cilantro, oregano and cumin.
Add olive oil and squeeze lime and orange juices. Stir and set aside.
Pork:
Add a bit of olive oil to dutch oven at medium heat, then add pork, browning all sides.
Pour marinade over pork, put lid on top and place on low heat. Allow to steam cook, trying not to lift lid too often, for 2-3 hours. I checked on mine to be sure the marinade and meat at bottom wasn’t burning.