Preheat the oven to 400 degrees F. Allow the pork to stand at room temperature for 30 minutes.
Place the pork, fat side up, in a roasting pan just large enough to hold it comfortably. In the bowl of a food processor fitted with a steel blade process the garlic, rosemary, lemon zest, and fennel seeds until roughly chopped. Add the olive oil, mustard, salt and pepper and process until it forms a smooth paste. Rub the paste on top of the pork and roast for 1 to 1 1/4 hours, or until the internal temperature reaches 140 degrees F. Remove from the oven, transfer to a cutting board, and cover with aluminum foil. Allow to sit for 20 minutes, then remove the strings, slice between the bones and serve warm.
2007, Ina Garten, All Rights Reserved