Crispy Pork Belly

1 kg (2 lb) pork belly, skin on, not scored (about 3–3.5 cm / 1.2–1.6 inches thick)
1½ teaspoons olive oil
1 teaspoon salt
¼ teaspoon black pepper
½ teaspoon fennel powder (ground fennel seeds)

Dry the pork belly skin thoroughly with paper towels. For best results, leave the pork uncovered, skin side up, in the fridge overnight to dry the skin.
Preheat the oven to 140°C / 285°F (120°C fan).
Drizzle 1 teaspoon of olive oil over the flesh side only. Sprinkle with ½ teaspoon salt, black pepper, and fennel powder if using. Rub evenly over the flesh and sides.
Place the pork belly skin side up on a sheet of foil. Fold the foil up around the pork to form a snug boat that covers the flesh but leaves the skin exposed. Seal well and place on a baking tray.
Rub the remaining ½ teaspoon olive oil over the skin, then sprinkle evenly with the remaining salt.
Roast for 2½ hours. After 1½ hours, remove from the oven, tighten the foil around the pork, and return to the oven for the remaining time.
Remove the pork from the oven and take it out of the foil. Place it skin side up on a rack set over a tray (or directly on a tray). Use scrunched foil under the pork if needed to keep the skin level.
Increase the oven temperature to 240°C / 465°F. Roast for about 30 minutes until the skin is puffed, golden, and crispy. Rotate the tray as needed and cover any overly dark spots with foil.
Remove from the oven and rest for 10 minutes.