Using a vegetable peeler, peel and the pears and cut a small amount from the bottom of each pear so that stands up straight. Set aside. Using the same peeler, remove the zest from the orange in large strips, being careful to include as little of the white pith as possible. In a large (3 quart) pot combine the riesling, sugar, cinnamon sticks, star anise , ginger and orange zest. Over medium heat, stir until the sugar is dissolved. Add the pears and then enough water to barely cover the pears. Bring liquid to a simmer and simmer for 1 to 1 ¼ hours until the pears are easily pierced with a cake tester (I use a cake tester so that I can test the tenderness of the entire pear). When pears are tender, remove from the poaching liquid and set aside. Bring poaching liquid to a boil and boil until reduced by ½ and liquid has thickened to a light syrup consistency. Taste. Depending upon how sweet your riesling is you may wish to add additional sugar - add by tablespoons, stirring to dissolve. Pears can be made 1 day ahead - refrigerate pears and syrup in a covered container. Warm pears and syrup before serving. To serve, place a pear on each plate and drizzle with the syrup. You can remove the orange zest and cut into small slivers for garnish if you like.