Start by ensuring that all your liquid ingredients are super cold. Put the butter and sour cream in the freezer, and put ice in your water ahead of using it.

Mix the flours, xanthan gum and salt together in a large mixing bowl. Add the cubes of cold butter and coat them with the flour mix. Use your fingertips to gently rub the butter into the flour mixture. At first it might be slow and difficult if the butter is very cold, but gradually you’ll warm it with the heat of your hands and it will start to be more flexible. You don’t want to completely melt the butter – just rub it into the flour in little sheets. This is what makes the pastry puffy and flaky. Think of the hand motion as being the same as the one you make to signal someone is rich.

Once the butter has been rubbed into the flour mixture, it should have visible butter chunks but look dry on the whole.

Add the sour cream in dollops and use a spoon or your hard to incorporate it. It will get a little messy.

Once most of the sour cream has been incorporated, use your hands to gently bring the dough together without smushing the butter bits.

Add the ice water, a tablespoon at a time. Use your hands to bring the dough together between each teaspoon, and stop as soon as the dough is smooth. I’ve found this dough can take anywhere from 3 1/2 – 5 tablespoons of water. Yours might be different, but go by feel and stop as soon as it forms a ball with no dry flour bits.

Tightly wrap the dough in a beeswax wrap or cling film and place in the fridge for 30 minutes to an hour. Your pastry is then ready to roll out and use!

You can freeze the pastry, well wrapped in an airtight container. Allow to come to temperature before attempting to roll out.