Split the vanilla beans in half lengthwise then cut crosswise into 1-inch pieces. Put the vanilla into a food processor and blitz until the vanilla is in fine pieces (or as close as you can get in your processor), scraping the sides down periodically as needed. Add the sugar and process for another two minutes to incorporate.

Sift the mixture to catch any large pieces and place them back in the processor to blitz further (you may want to do this a few times depending on how fine you want to get the pieces). The mixture will be ashy colored and have flecks of vanilla.

Store in an airtight container.