Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

In a medium bowl, whisk together the gluten-free multipurpose flour, baking powder, poppyseeds, and kosher salt.

In a large mixing bowl, combine the granulated sugar and lemon zest by rubbing them together.

Add the flour mixture into the sugar-zest bowl, stirring to combine well.

In another bowl, whisk together the kefir, egg, and fresh lemon juice until frothy.

Turn the shaggy dough out onto a lightly floured surface and shape it into a rectangle.

Form the dough into a 6-inch disk and wrap it in plastic wrap; chill for at least 10 minutes.

Remove the dough and cut it into eight equal wedges; place on the baking sheet.

Bake the scones for 22-26 minutes, or until golden brown.

Let the scones cool for 10 minutes and prepare the glaze by mixing powdered sugar with lemon juice.