In a sauce pan bring 2 cups of water to the boil. Add the salt and sugar, stirring to dissolve. Add the spices and boil for 3 minutes. Remove from heat and add 4 cups of cold water. Allow to come to room temperature. Place pork loin in a container large enough to accommodate with brining liquid (See Note 1). Seal and refrigerate fro at least 8 hours.
Cook broccoli rabe in heavily salted boiling water for 3 minutes. Plunge into an ice bath for 1 minute. Drain well. Wrap broccoli rabe in paper towels and squeeze dry. Chop rabe into 1 1/2-inch pieces.
Place in bowl with 1 tablespoon oil, 1/4 teaspoon salt, pepper, and garlic; stir well (See Note 2).
Preheat oven to 375°F. To butterfly the pork loin: Use a sharpened knife. Cut down but not through on one long side of the pork loin, about 3/4" from edge and down through to 3/4". Now with knife parallel to cutting board, continue slicing lengthwise, rolling loin in other hand like you're unrolling a scroll.
Arrange prosciutto in layer to cover top of butterflied pork loin. Spread broccoli rabe mixture on top, leaving a 1-inch border. Working from a short end, roll up and secure with kitchen twine every 2 inches.
In a large skillet, brown it in olive oil on all sides. Place in a roasting pan on top of sliced onion, chicken stock and white wine.
Cover with aluminum foil and roast at 375°F for 45 minutes (See Note 3). Remove foil and continue roasting for 15 minutes, basting with pan drippings and balsamic syrup.
In a sauce pan bring the water, sugar and cranberries to a boil. Reduce heat and add the orange extract. Stir often and allow to break down and thicken on low heat for 15 minutes. Set aside.
We're looking for a super moist pork loin with an internal temperature of 150°F. After roasting, allow it to rest for 20 minutes and keep it lightly covered with the foil. Either use the pan drippings to pour on the slices at serving or put all pan drippings and onions in a blender to purée and thicken as a sauce.
Serve with cranberry orange sauce.