Preheat oven to 325 degrees F.
Prepare the pork. Combine salt, pepper, cumin, oregano, paprika, onion powder, and olive oil. Spread rub evenly onto the pork. Lay chopped onion and garlic into a deep baking dish. Place pork on top and pour the juice of 2 oranges and chicken broth into the pan. Cover and bake for 2 ½ hours or until the meat easily shred apart. Remove from oven and shred the meat using two forks. Keep warm.
Meanwhile, prepare the chipotle aioli. Blend together lime juice, chipotle and mayonnaise until smooth. Season with salt and pepper. Set aside.
Make the pico de gallo. Finely chop the tomatoes and combine with finely chopped red onion, cilantro, and lime juice. Season with salt and pepper. Set aside.
Thinly slice the jalapenos. Heat 2 teaspoon oil in a saute pan over medium heat and cook the jalapenos until lightly charred and softened. Set aside.
Prepare the fried avocado. Cut the avocado in half, discarding the pit. Scoop out the flesh using a spoon and slice into ¼ inch thick slices. Coat the sliced avocado in the flour, followed by the egg then panko. Heat oil in frying pan over medium-high heat. Carefully place the avocado into the hot oil and fry until golden brown. Flip and cook on the other side. Remove and place on paper towels to blot the excess oil. Sprinkle with salt. Set aside.
Toast the bread. Assemble the sandwiches. Spread chipotle mayo on the buns followed by carnitas, Monterey Jack cheese, fried avocado, roasted jalapenos, and pico de gallo. Serve immediately.