Pour boiling water over pork skin the night before and discard water.
Baste joint with cider vinegar and refrigerate uncovered overnight.
Spread pork with dripping, bay leaves, garlic, salt, and pepper.
Preheat the oven to 200°C.
Roast pork skin-side up on a wire rack for one hour.
Reduce oven to 180°C and prep tray with vegetables, thyme, oil, and water.
Transfer pork fat to the vegetable tray and place tray under the pork.
Roast for one more hour while basting vegetables with pork juices.
Remove pork and let it rest for 15 minutes.
Toss spinach with the roasted vegetables and drain excess fat.
Carve crackling separately and serve pork with vegetables and gravy.