In a medium-sized saucepan, combine the water and granulated sugar. If using a vanilla bean, split it lengthwise down the middle with a sharp knife and scrape the tiny black seeds into the sugar-water mixture. Drop in the empty pod as well. If using vanilla extract, add it now.
If using a vanilla bean, scrape the tiny black seeds into the sugar-water mixture and drop in the empty pod. If using vanilla extract, add it now. Bring the mixture to a gentle boil over medium-high heat, stirring until the sugar has completely dissolved. This will create a fragrant vanilla syrup.
While the syrup is heating, bring a separate small pot of water to a boil. Gently lower the peaches into the boiling water for about 45-60 seconds. Using a slotted spoon, carefully remove the peaches from the water and place them in a bowl of ice water to stop the cooking process and help the peaches retain their shape and texture.
To prepare the raspberry sauce, in a small saucepan, combine the raspberries with 1/2 cup of water, the sugar, and the powdered sugar. Bring the mixture to a gentle simmer over medium heat, stirring occasionally.
Once the sauce has thickened slightly, remove it from the heat and stir in the vanilla extract and lemon juice. Let the sauce cool slightly before using as a topping for the poached peaches.