Rum Caviar tutorial : To drink or taste on dessert

Via  Molecular Gastronomy

Fill your tall, narrow glass with vegetable oil. The taller your glass is, the better it will work, because this is what the hot rum mixture needs to travel through to cool off and solidify. If the glass is too short, the spheres may join at the bottom and you’ll have one giant lump of rum jelly. Place the glass of oil in the freezer and chill for 30 minutes.