In a large bowl, beat the eggs and sugar together with an electric mixer until thick and pale, about 10 minutes. Stir in the kirsch, salt, and anise seed. Use a sturdy spoon to stir in the flour. Add additional flour if needed to form a soft dough. Cover the dough with plastic wrap, and refrigerate overnight.
Divide the dough into two 1/2 inch thick ropes, and cut each rope into 2 inch long pieces. Place the pieces onto the prepared baking sheet, and cut three diagonal slits into one side of each piece. Bend the cookies to open the slits, flaring out the cuts. Cover loosely with a tea towel and allow to dry in a cool area for 24 hours.
Preheat oven to 325 degrees F (165 degrees C). Lightly grease a baking sheet.
Bake the cookies in the preheated oven for 15 minutes. They should not turn brown on top, and be only lightly colored on the bottom. Remove from the oven, and let stand in a cool place for 3 or 4 days. They will be rock hard at first, but will soften over time. Place the cookies in a cookie tin separated by sheets of waxed paper. Age 2 to 3 weeks to allow the flavor to mature.