Sio bak is mostly waiting. The actual cooking is straightforward. What separates good crackling from a sheet of leather is how dry the skin was before it went anywhere near heat, and almost all of that happens in the fridge the day before.
Fair warning on the other end of it: this dish makes a mess of an oven. Fat spits, sugar in the marinade caramelises onto the cavity walls, and the salt crust sheds. Plan for the cleanup as part of the recipe, because it is.
What you need
- 1kg pork belly, skin on, in one piece, as even in thickness as you can get
- 2 tbsp coarse sea salt for the crust, plus 1 tsp fine salt for the meat
- 1 tsp five spice powder
- 1 tsp sugar
- 1 tbsp Shaoxing wine
- Half tsp white pepper
- 1 tbsp white vinegar
Two days before, or at least overnight
- Boil a kettle. Hold the belly skin-side up and pour boiling water over the skin until it tightens and blanches. Pat completely dry.
- Prick the skin all over with a metal skewer or a meat pricker. Hundreds of holes. Go through the skin but not into the fat layer below, or the meat juices will bubble up and ruin the surface.
- Flip it. Rub the fine salt, five spice, sugar, wine and pepper into the meat side only. Keep all of it off the skin.
- Turn it back over, brush the skin with the vinegar, and leave it uncovered in the fridge for at least 12 hours. Two nights is better. The fridge is a dehydrator and dry skin is the whole game.
Roasting day
- Take it out an hour ahead. Pat the skin dry again.
- Wrap the sides and base in foil so only the skin is exposed, forming a shallow foil tray around the meat. Pack the coarse salt across the skin in an even layer about 5mm thick.
- Roast at 160C for 90 minutes. Nothing dramatic should happen. This is rendering, not browning.
- Take it out, lift the salt crust off in one piece and discard it. Scrape off any that stuck. The skin underneath will look pale and slightly leathery. That is correct.
- Turn the oven to its highest grill setting and go back in for 15 to 25 minutes, watching it constantly. The skin will blister and pop across the surface. Rotate the tray if one corner is running ahead.
- Rest 15 minutes, then cut with a heavy cleaver, skin side down, in one decisive motion.
The sound the knife makes tells you whether it worked. Crackling should crack.
The cleanup, which is the real reason to pick a particular oven
Twenty minutes under a full grill with exposed pork fat coats a cavity. If you make this more than twice a year, a self-cleaning oven pays for itself in Sunday evenings.
Two here do it by burning residue to ash rather than asking you to scrub. The Fujioh FV-EL62 is a 72 litre oven with pyrolytic self-clean, a heat shield coating rated to 445C, a four-layer glass door and 14 functions. The Mayer MMDO15P is 75 litres with 14 functions, fully extendable telescopic rails, and a pyrolysis cycle Mayer states runs at 500C, reducing residue to ash you wipe off with a damp cloth.
The telescopic rails on the MMDO15P are not a luxury for this dish specifically. Pulling a 1kg slab of pork and a tray of rendered fat out of a hot oven on a shelf that wants to tip is how people get burned.
More options in Built-in Ovens and 60cm Built-in Ovens.
Questions people ask
Why is my crackling chewy instead of crisp?
Moisture in the skin, almost always. The skin needs to be bone dry before high heat, which means at least 12 hours uncovered in the fridge and a thorough pat-down before roasting. Prick the skin properly too, or steam trapped underneath softens it from below.
What does the salt crust actually do?
It draws moisture out of the skin during the low, slow phase and shields it from browning too early. You lift it off before the high-heat stage. Without it, the skin colours before it has dried, and colour without dryness is leather.
Can I skip the two day fridge rest?
Overnight is the minimum I would attempt. Anything shorter and the skin has not lost enough water. If you are short on time, a fan running on the skin at room temperature for a few hours helps, but it is a poor substitute.
Do I need a pyrolytic oven for this?
No, but you will spend the evening scrubbing if you do not have one. A hydrolytic or steam-assisted clean cycle handles it too, just with a wipe at the end. Line the base of the oven with foil either way, keeping vents clear.
How do I stop the skin burning in patches?
Uneven thickness. Choose a belly that is level across its length, and if one end is thinner, shield it with foil during the grill stage. Rotate the tray halfway through and do not walk away.
Cook next
Same oven, same grill, far less waiting: sambal stingray in banana leaf. If you are still specifying the oven, oven capacity explained and how to measure for a built-in oven are the two to read first.