Preheat the oven to 400 degrees. Mix the pressed garlic cloves, mustard, rosemary, lemon peel, sea salt and pepper together. Rub this mixture over the entire pork roast. Place the pork, fat side down, into a 13 x 9 x 2-inch non-stick roasting pan. Roast the pork 30 minutes, then turn roast fat side up and roast until a thermometer inserted into the center of the roast registers 155 degrees, about 25 minutes longer. Remove from the oven and let the roast cool for about 10 minutes.
Deglaze the roasting pan (with warm chicken stock if needed) and pour into a small saucepan over low heat. Cut the pork crosswise into thin 1/3-inch-thick slices and arrange overlapping slices on a platter. Drizzle the pan juices over in a zigzag pattern and garnish with fresh rosemary sprigs.
Makes 8 servings (Any leftovers are great for sandwiches.)