4 ounces raisins (a mix of golden and purple raisins is nice)
11/2 tablespoons fresh rosemary leaves
1 tablespoon thinly sliced fresh sage leaves
2 cloves garlic, minced
1 shallot, peeled and thinly sliced
1/4 teaspoon fennel seeds
Pinch of ground cloves
Kosher salt and freshly ground black pepper.
2 large yellow onions sliced into 1/2"-thick slices (for bottom of roasting pan)
One hour before cooking, take pork out of the fridge to warm up.
Place raisins in a small bowl, and add enough boiling water to cover them. Set aside to soak for several minutes. Drain.
When the pork has warmed up, preheat oven to 375°F.
Slice pork lengthwise, without cutting all the way through, so that it opens like a book. (You want to open up the meat so that you can stuff it and then tie it back up. The goal is to get a wide, even piece of meat with the same thickness all around).
Stir in rosemary, sage, garlic, shallot, fennel, cloves, and 1/2 teaspoon salt.
Place this herb mixture in the center of the pork loin, roll it up, and tie with 3 pieces of kitchen twine.
Set the pork on a bed of thickly-sliced onions in a roasting pan just larger than the meat.
Roast for about 1 hour, or until the skin is crisp and an instant-read thermometer reads 145°F in the thickest part of the pork. Take the roast out of the oven, transfer it to a cutting board, and let it rest for 20 minutes before carving it into thick slices.