1. In a bowl, combine the sugar with the lemon and mandarin (orange) zests, add the flour, salt and eggs. Gradually mix in the milk.
2. Let the batter rest for at least 1 hour in the fridge, covered with plastic wrap.
3. Before making the crepes, blend in the browned butter - it not only adds flavor, but allows you to cook the crepes without too much fat and to brown them more evenly.
4. Spread the butter in the skillet with a piece of paper towel. Don't worry... the first crepe never looks very good!
5. Cook the crepes according to the usual method.
6. Fold the crepes and place them into a serving dish; pour on the Grand Marnier.

Precautions

• the pan should always be very flat and non-stick or a steel (Lyon-style) pan heavy enough to distribute the heat evenly.
• use a flexible spatula if you're not daring enough to flip the crepes.
• use a ladle that will hold enough batter for one crepe
• have 2 plates ready: one placed on a saucepan of hot water where you can pile the crepes, and the other turned over to cover them in order to keep them hot.