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

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

In a large mixing bowl, combine granulated sugar with the fresh lemon zest and rub to infuse the sugar with flavor.

Add the dry ingredients to the lemon zest sugar bowl and stir until just combined.

Cut the cold unsalted butter into the flour mixture until it resembles coarse crumbs.

In a separate bowl, whisk together the kefir, egg, and lemon juice, then fold into the dry ingredients until just combined.

Turn the dough onto the baking sheet and pat into a rectangle of 1-inch thick, then fold over three times.

Shape the dough into a 6-inch round disk, cover, and refrigerate for 10 minutes before cutting into 8 equal wedges.

Brush the tops of the scones with kefir and sprinkle raw sugar on top.

Bake for 22-26 minutes until golden brown, watching to prevent overbaking.

Let the scones cool on the baking sheet for 10 minutes before glazing with a mixture of powdered sugar and lemon juice.

Drizzle the glaze over each scone and serve warm with tea or coffee.