1. Pat pork shoulder skin dry and smooth out any wrinkles as best you can. If time permits, leave it uncovered in the fridge overnight to dry out.

2. Preheat oven to 220C fan-forced (240C conventional).

3. Combine 1½ tsp salt, 1 tsp pepper, all the fennel seeds and 1 tbsp olive oil in a small bowl, then rub all over the pork flesh (not skin).

4. Flip the pork and drizzle skin with 1 tsp of oil and rub all over. Sprinkle with the remaining 1½ tsp salt.

5. Place the garlic and onions in a roasting pan, cut side up. Place the pork on top, skin side up, using the onions and garlic to position the pork so the skin is as level as possible.

6. Add the wine to the pan, taking care to not wet the skin.

7. Transfer to the oven and immediately turn temperature down to 140C fan-forced (160C conventional) and roast for 2½ hours.

8. At 1½ hours, take it out of the oven and use balls of scrunched-up foil to adjust the pork so the skin is as level as possible, and dab away any oil pooled in crevices on the skin with paper towels. Then return to the oven for another 1 hour.

9. At 2½ hours, remove the pork from the oven and check there is still liquid in the pan (add a little water if needed).

10. Turn the oven up to 250C fan-forced (and same temperature for conventional), or as high as it will go, if your oven will not go that high.

11. Return the pork to the oven for 30 to 40 minutes, rotating the pan every 10 minutes. Cover the crackling that's already crisp with foil (secured with water-soaked toothpicks) and continue to roast exposed parts until the skin is crisp all over. (Remember, the higher points will bubble faster and better.)

12. Transfer the pork to a serving platter, cover loosely with foil (don't worry, the crackling will stay super crisp) and rest for 20 minutes, or up to 1 hour while you make the gravy.

13. To make the gravy, scoop 3 tablespoons of fat from the roasting pan into a saucepan. Heat the fat over medium heat, then whisk in flour and cook for 30 seconds. Pour in the stock while whisking to prevent lumps forming. Discard surplus fat from the remaining pan juices and strain the juices into the saucepan. Simmer for 3 to 5 minutes, until it has a thin gravy consistency – it will thicken more as it cools – adding salt and pepper to taste.

14. To serve, slice the pork with a serrated knife. Pour gravy into a jug and serve separately.

Tips:

To guarantee perfect crackling, buy freshly cut boneless pork shoulder that has not been scored, rolled, tied, or vacuum-packed. The drier and smoother the skin, the more perfect the crackling.

If your pork was bought in a vacuum-sealed packet, the skin will be quite wet and wrinkly. Unpack it, flatten out the skin as best you can, pat dry well and leave uncovered in the fridge, preferably overnight (minimum 1 hour).

Try to buy pork with skin that has not been scored. If the scores are cut too deep, meat juice will bubble up through the cuts and the skin won't crisp. This is the single biggest cause of crackling fails!

This recipe features in Nagi Maehashi's festive spread for $20 a head.