For the sandwich: ciabatta rolls red onion, thinly sliced arugula, red wine vinegar (to dress arugula)
Using a mortar and pestle, combine garlic, herbs, lemon zest, spices, salt and pepper, and a little olive oil into a loose paste. Set aside.
Thoroughly pat dry the pork belly. To ensure the crispiest skin, you can leave the pork belly skin up, uncovered, in the fridge overnight. Score the skin.
Preheat oven to 400°F. With the pork at room temperature, spread the seasoned herb mixture over the meat side. Spiral the slabs of meat and use butcher's twine to keep the shape. Rub the skin liberally with salt. Cover loosely with foil, place on a roasting or baking rack, and roast for 40 minutes. Remove foil, brush the skin with olive oil, and continue roasting for another hour or until the skin is crispy and the meat is tender.
Remove from oven and allow to rest for 8-10 minutes. Slice and serve on toasted ciabatta rolls with sliced red onion and red wine vinegar dress arugula.