Feed the mother a couple of hours before you need to use it. Wait until it is active and bubbly. Don't try it with a sleepy starter it won't work. Then remove 150g from your mother and place in a mixing bowl . Mix with the flours, add the xantham gum, baking powder, salt and honey. Add the tea cup of water and mix. You need to form a smooth ball - and it musn't be too sticky so you may need to add a little flour and or water until you have that non sticky texture. Make a nice smooth ball.
Flour a stiff cloth with rice flour. place in a round bowl and leave to prove for 3 hours [less on a warm day]. It should increase in size but will not be as dramatic as normal sourdough rise. The floured cloth should keep it from sticking. Grease a baking tray and then roll out the ball out on it. Make a couple of cuts for the steam. Bake in a hot oven with some water in a cast iron container at the bottom for steam. Bake for 30/40 minutes. Move to the top of the oven to crisp the top.
One final point. Keep this away from your regular sourdough starter and implements so to avoid cross contamination.
half a tea spoon xthanan gum
half a tea spoon of baking powder
White flour 200g
chestnut flour 50g
teaspoon of salt
dessert spoon of honey
tea cup of water