Prepare the Dough: In a large mixing bowl, whisk together the egg, sugar, and salt until smooth. Add the yogurt (or kefir), vegetable oil, and vanilla extract. Mix well.
Incorporate Dry Ingredients: Gradually add the flour and baking powder, stirring until a soft, slightly sticky dough forms.
Shape the Cookies: Roll the dough out on a lightly floured surface to about ½-inch thickness. Use cookie cutters or shape small rounds by hand.
Sprinkle with Sugar: Lightly brush the tops with water and sprinkle with extra sugar for a crispy, caramelized finish.
Bake: Preheat the oven to 350°F (175°C) and place the cookies on a lined baking sheet. Bake for 12–15 minutes, or until the edges are lightly golden.
Cool & Serve: Let the cookies cool on a wire rack before serving. Enjoy as is or decorate with icing for a festive touch!