Peel the pears carefully, leaving the stems intact if you like. Use a melon baller or small spoon to scoop out the core from the bottom of each pear, being careful not to cut all the way through. This will help them stand upright while poaching.
In a large pot, combine the water, sugar, star anise, lemon zest, lemon juice, and cinnamon stick (if using). Stir until the sugar is dissolved. This mixture will infuse the pears with flavor as they cook.
Gently place the prepared pears into the poaching liquid. Make sure the liquid covers most of the pears; if not, add a little more water. Bring the liquid to a simmer over medium heat.
Reduce the heat to low, cover the pot, and let the pears simmer for about 20-30 minutes, or until they are tender but still hold their shape. You can test for doneness by gently piercing a pear with a fork; it should slide in easily.
Carefully remove the pears from the poaching liquid and place them in a bowl. Let them cool slightly.
If you want a thicker syrup, increase the heat to medium-high and boil the poaching liquid for about 10-15 minutes, or until it has reduced to your desired consistency. Be sure to remove the star anise and cinnamon stick before boiling.
Once the pears have cooled slightly, you can serve them warm or cold. Drizzle the reduced poaching liquid over the pears before serving for extra flavor.