Preheat oven to 300 degrees. Stir together port, honey, star anise, cinnamon sticks, peppercorns, and vanilla bean in a large roasting pan. Add raisins. Cut a 1/4-inch-thick slice from bottom of each pear to level, and then place pears in pan.
Bake pears, basting with pan juices every 15 minutes, until skins are wrinkled and pears are golden brown and tender, about 2 1/2 hours. Let cool in pan on a wire rack.
Arrange pears on a serving platter. Pass pan syrup through a fine sieve set over a bowl; discard solids. Drizzle syrup over pears.