Preheat the oven to 425°F.

In a large measuring cup, add the white vinegar to the milk and stir to combine. Let stand for 5 minutes in the refrigerator to stay cold. (homemade buttermilk)

In a large bowl, mix together the gluten-free flour, sugar, baking powder, baking soda, and salt.

Add the cold butter and cut it into the gluten-free flour mixture with a pastry cutter, a fork, or your fingers until it resembles small peas.

Stir in the raisins. If you are not a fan of dried fruit, you can leave it out.

Whisk the egg and homemade buttermilk (milk and vinegar mixture) together.

Make a well in the center of the dry ingredients and pour the egg and buttermilk mixture into the flour mixture.

Using a large spoon, mix the gluten-free flour mixture and milk mixture together to form a shaggy dough. The dough will be soft but not too sticky. Do not over-mix the dough, or you will end up with tough bread.

Sprinkle 1 tablespoon of gluten-free flour onto parchment paper. Turn the dough onto the parchment paper and gently bring the dough together into a round, about 8-inches by 8-inches. If the dough is sticking to your hands, lightly wet your hands with water.

Gently fold the dough over on itself 2 times. You do this by folding the dough in half on top of itself and then doing it a second time. Form the dough back into an 8-inch by 8-inch round.

Place the round dough onto a greased baking cast iron skillet, baking sheet, or baking pan.

Using a knife, score the bread with a deep cross on top. Do not skip this step because it helps the middle of the bread bake though.

Bake for 15 minutes at 425°F, then turn down the oven to 400°F and bake for 30 minutes more. When done, the loaf will be golden brown and sound slightly hollow when tapped on the bottom.

Allow the loaf to cool for a few minutes then, and then place it on a wire rack to cool.