Combine sugar, salt and spices in a large pot. Add 4 1/4 quarts water, and bring to a boil. Cool, then transfer to a large bowl and add pork. Let stand, loosely covered, for 3 days in refrigerator.
2
Heat oven to 375 degrees. Place onions in a roasting pan. Rinse pork, score skin with a sharp knife and place on onions. Rub skin with a bit of olive oil, and season lightly with sea salt. Roast, uncovered, 1 1/2 to 2 hours; do not let burn. Skin should be crisp; if not, transfer to hot broiler. Cut pork in thick slices, and serve with onions.