In a large mixing bowl, place pork pieces, orange peel, juice, chicken stock, brown sugar, apple cider vinegar, soy sauce, dark sweet soy sauce, Angostura aromatic bitters, ginger, salt and pepper. Mix everything together well in the bowl, coating all over, allow pork pieces to infuse in the marinade for 30 minutes.
For the carrot pickle, mix together carrot, vinegar, sugar and salt, in a large mixing bowl, allow the carrot to pickle in the juices, leave aside until serving.
In a heavy based saucepan on medium high heat, pour in vegetable oil. Transfer the pork pieces into the pan (reserving the marinade) and cook for 5 minutes or until golden brown. Add the onion to the pan and toss until well combined. Pour over reserved marinade. Reduce heat to low and cook for 1 hour or until the sauce has thickened and the pork is fork tender.
To make Nuoc Cham Dressing, mix together fish sauce, sugar, vinegar, garlic and chilli. Stir well and set aside.
Serve the pork the carrot pickle, nuoc cham and fresh herbs, if using.
