Use the tip of a paring knife to gently scrape out the inside of the bean to get the pulp and vanilla bean seeds.
Place sugar in a bowl and add the vanilla seeds.
Use a whisk to lightly stir the sugar. This will help distribute the seeds and pulp.
The seeds are sticky and are sometimes difficult to separate. You can use your fingers to rub any clumps of vanilla bean into the sugar.
Place sugar into a jar and add the scraped vanilla bean halves. The bean still has a lot of flavor.
Place a lid on the jar and let the flavors infuse the sugar for at least a week.
Shake the jar to help release any sugar clumps and help redistribute the vanilla.
Notes
I prefer to use a whisk for making this sugar, but a food processor also works. If using a food processor, just pulse a few times to distribute the vanilla into the sugar. Any longer and you'll end up with a superfine sugar.
Vanilla beans are moist and will cause the sugar to clump. Just shake the jar to loosen the clumps.
For maximum flavor, allow your vanilla sugar to develop for at least a week. However, the sugar can be used right away. It just won't have full flavor.
Use a 1:1 replacement for regular granulated sugar in any recipe where you'd like to enhance the vanilla. Don't eliminate the vanilla extract if your recipe calls for it.