1. Place parve milk, vanilla, and rum in blender and blend well (or use an immersion blender). Add yolks, sugar, salt, flour, and melted margarine. Blend for 30 seconds.
2. Transfer batter to an airtight container. Refrigerate for two hours or overnight.
3. Brush a six- and- a- half- to seven-inch (16- and- 1/2- to 18-centimeter) frying pan with oil. Place over medium heat to heat the oil. Remove pan from heat.
4. Pour two tablespoons of batter in the center of the pan. Tilt in all directions. Return pan to flame for one minute.
5. Jerk pan sharply back and forth to loosen the crepe. Lift the edges and turn over. Cook for another 30 seconds. Slide the finished crepe onto a paper-towel-lined towel. Grease pan and repeat until batter is finished.