Place the pork in a large dutch oven with the orange juice, lime juice, salsa and salt. Add enough water to barely cover the meat. Bring to a boil. Once boiling, reduce heat to medium low and simmer with the lid on for 2 hours, at which point the pork should be falling apart to the touch. Turn the heat up to medium high, and continue to cook the pork for 45 minutes, uncovered, stirring every once in a while, until all the liquid has evaporated and the pork fat has been rendered. Parts of the pork should be caramelized and golden brown. Remove the dutch oven from the stove and season with salt and pepper as needed.
To make the corn salsa, roast the poblano peppers on a grill, an open flame until charred. Place in a bowl and seal with plastic wrap. Let sit 10 minutes. Meanwhile combine the corn, onion, cilantro, lime juice, and salt. Once peppers have “steamed”, remove the charred skin and dice the peppers and add to the bowl with the other ingredients. Toss to combine, season to taste with salt, and set aside.
Stuff the tortillas with the carnitas and corn salsa mixture and top with salsa, guacamole, sour cream and the shredded cheese. Garnish with cilantro as needed and serve.