Gluten Free Cornish Pasty

Name: Gluten Free Cornish Pasty
Cook time: 45 min
Total time: 45 min
Cuisine: European, British
Ingredients: 3 cups all-purpose gluten-free flour blend, one that includes xanthan gum. (Otherwise, add 3/4 tsp.) My favourite flour for this recipe is; 1 tsp. Sugar (I used fine coconut sugar); 1/2 tsp. Xanthan gum (this is in addition to the xanthan gum in the flour blend); 1/2 tsp. Baking soda; 1 cup salted butter, divided (place the butter in the freezer for 15 minutes before using); 1 cup sour cream, chilled; 4 - 8 Tbsp. Ice water or as needed; FILLING; 1 lb. sirloin steak, thinly sliced; 3/4 lb. Yukon gold potatoes, peeled and cut into 1/4 inch size cubes (should make about 3 cups); 1 medium yellow onion, diced; 1 small rutabaga, peeled and cut into small cubes (should make about 1 1/4 cups); Sea salt and GF ground black pepper; 1 large egg beaten, for brushing