If using banana leaves place them in a slow cooker or 7 qt. Dutch oven which has been lightly sprayed with Pam.
In a skillet heat oil until hot and brown pork roast on each side. Place pork roast on banana leaves and sprinkle the top with chili seasoning.
Top with onion slices. Wrap leaves around pork. Pour water over the leaves. Cook pork roast in 350 degree oven for 3 hours, or 8 hours on low in the slow cooker
When cooked, remove roast and let cool enough to shred meat with forks.
In the meantime, heat the tomato sauce, orange oil or zest, lime juice and red pepper flakes in a skillet. Add the cooked pork and coat well. Heat on low for about 15 minutes to let flavors blend.
Heat corn tortillas. Spoon some of the meat mixture on the tortillas. Simply place a dollop of sour cream on each taco and a slice of avocado. A squeeze of fresh lime is always welcome. Garnish with chopped cilantro.