Whisk together the warm water, yeast and 1 teaspoon of sugar. Set aside to develop.
Mix together the flours, corn starch, xanthan gum, salt and baking powder.
In a separate bowl beat together the egg, oil, garlic and vinegar.
Combine the two mixtures, until thoroughly mixed. The dough will be rather sticky.
Dust a kneading surface with gluten free flour (I use rice flour, since it is least expensive.) Form the dough into ball and knead a little until it is handle-able. Do not overwork it.
Stretch and form the dough into a crust shape. Leave it a little thick at this point.
Coat a baking sheet with non-stick cooking spray or very lightly oil it.
Transfer dough to pan. Press and stretch the dough until crust is thin.
Cover loosely with plastic wrap and put in a warm place to rise for 30-40 minutes.
Preheat oven to 400 degrees.
Bake crust for 7-8 minutes. Remove and add toppings.
Bake for another 10 minutes.
Cool on a rack or double folded towel, to keep crust crispy.