Take the cap of the vanilla extract bottle and pass it over the sugar. 3 grams of sugar is roughly 1/10 of an ounce, so I doubt that there would be much vanilla flavour to worry about. You can make your own vanilla sugar by cutting up a vanilla bean and letting it sit in some sugar for a while. You can even use vanilla beans that you have used for a cooked dish, like custard. If desperate, you can put a drop or two of extract in a cup of sugar and shake it around to get the flavour mixed up really well.