Preheat an oven to 190℃ / 374 F. Soak an orange with boiling water for one and a half minutes to remove the wax. Take out from hot water, wash thoroughly with water, and wipe off any water.

Zest an orange. Please zest only the orange surface thinly. Chop the walnuts roughly.

Put cake flour, bread flour, baking powder, and granulated sugar in a large bowl. Stir it well. Add the beaten egg and fold roughly.

Add the walnuts and fold roughly. Add the orange zest and fold to distribute evenly.

Flour your work surface, and place the dough on it. Flour the dough, and use your hand to lightly knead it several times until the dough holds together. Please Be careful not to knead too much. Roll it and form it into a log of 20-22 cm / 8-9 inches. Transfer it to a parchment-lined baking sheet.

Lower the oven to 170℃ / 338 F and bake for about 20 minutes until the edges are slightly brown. The dough should spread. Take it out and let it cool for 7 minutes. Preheat the oven to 190℃ / 374 F again.
Cut it a little diagonally to a width of about 2 cm / 0.8-inch to divide around 10-12 pieces. Arrange them on the baking sheet with the cross-section facing up.

Lower the oven to 170℃ / 338 F and bake for about 25 minutes until golden brown. If possible, take it out after 18-20 minutes, and turn each over quickly to bake it evenly. Cool them on a rack. It's all done.