Separate the egg whites from the yolks. Beat the yolks with the sugar. Then add the egg whites and beat well until the mixture is fluffy and forms a meringue. Squeeze the oranges and add 1 teaspoon baking soda to the juice. When it starts to foam, pour it into a large bowl along with the meringue.

Add the oil, orange zest, and mix well.

After sifting the flour with the baking powder, gradually add it to the mixture along with the vanilla. Add the flour in batches until the dough starts to pull away from your hands. You may need a little more flour (about 3.5–7 ounces or 100–200 grams extra). Shape the dough into any shape you like and place on a baking sheet lined with parchment paper. Brush all the cookies with a beaten egg (if making the full batch, you'll need 2 beaten eggs; for half a batch, 1 egg is enough).

Bake in a preheated oven at 400°F (200°C) with convection for about 20–25 minutes. The cookies will be crisp on the outside and soft on the inside. Good luck!