Begin by setting your oven to 425 degrees.
2 egg whites, beaten slightly
1 cup buttermilk, or 1 cup water and 1 envelope buttermilk powder
1 5/8 cups white rice flour (not glutinous, just white)
1/2 cup cornstarch
1/4 cup brown rice flour
1 tsp xanthan gum
2 tsp baking powder
1/4 tsp baking soda
Mix all dry ingredients in a large bowl with a whisk.
Cut in butter till the size of peas.
Mix eggs and water or buttermilk, if using.
Add to bowl of dry ingredients and butter.
Lightly spray a cookie sheet with oil or use lightly sprayed parchment on a sheet.
Drop biscuits onto sheet.
Makes about ten 2-inch biscuits.
Bake 15-20 minutes.