1 8–10 lb prok belly with skin
2 T olive oil
1 medium-size yellow onion
8 c chopped fresh collard greens
1 T fennel
4 T plus 1 t salt
1 c chopped fresh parsley
1/4 c minced garlic
2 T chopped fresh rosemary
4 t lemon zest
1 T pepper
Place pork skin side down on a work surface. Score in a cross-hatch pattern about 1 inch deep and 2 inches wide. Starting with short side, roll in a tight spiral cut a shallow line the length of the roll to show where it overlaps (you will keep all skin on the short side of that line. Unroll and turn skin side up. using the shallow line as a guide, remove skin from all meat that will be inside the roll. Score remaining meat in a cross-hatch pattern about 1/4-inch deep and 1 inch wide. Turn skin pork side down and set aside.
Heat oil in a large skillet over medium-high heat. Add onion and stir often, cooking until translucent (about 3 minutes). Add collard greens, fennel, and 1 t salt; cook stirring often until just wilted (about 2 minutes). remove from heat, let cool uncovered (about 10 minutes).
With skin side down, sprinkle pork belly evenly with parsley, garlic, rosemary, lemon, and pepper; the collard greens mixture; and the remaining 4 T salt. pat the mixture into the meat. Starting with the shorter, skin-removed side, re-roll into a tight spiral (skin should cover exterior but not be covered anywhere. Tie at 1-inch intervals with kitchen twine. Place in a roasting pan with a rack and chill 12 hours.
Preheat oven to 275. Bake until thickest portion of pork registers 160 degrees (4-6 hours). Remove from oven and increase heat to 500 degrees. Bake until skin is cripy and deeply browned (about 25 minutes); basting with drippings during the last 10 minutes. Remove from oven and let rest 30 minutes. Slice with a serrated knife and discard twine. Serve with Lemony Herb Sauce, parsley, and lemon wedges.
Lemony Herb Sauce
3 c chopped fresh parsley
1-1/2 t salt
3/4 t grated garlic
1 t lemon zest
6 T lemon juice
1/2 t black pepper
3/4 c olive oil
Stir together all ingredients except oil, add that last. Serve immediately at room temperature.