In a medium size bowl, combine the butter and sugar, and beat until fluffy. Add the egg whites one at a time, beating thoroughly before adding the next. Fold in flour and mustard seeds. Mix well, and refrigerate.
Grease baking sheet with butter. Drop spoonfuls of batter onto baking sheet, and smooth into desired shape. Bake for 5 minutes, until golden brown. Remove from the baking sheet with a pallet knife, and shape over a bottle turned on its side. Let tuilles harden over bottle, remove, and set aside.
To make the raspberry sorbet, puree raspberries and strain through a sieve. Combine the sugar and water in a saucepan and stir over gentle heat until sugar has dissolved. Turn heat up, and boil for 5 minutes until liquid forms a sticky syrup. Once the syrup has cooled, add the puree and the juice of 1 lemon. Freeze in an ice cream maker for 20 minutes. Alternatively, place mixture in a bowl and put in freezer. When edges begin to freeze, whisk an egg white, and fold into the partially frozen mixture. Return to freezer until frozen.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of C. Secard, Au Grain de Moutard, France