Preheat the oven to 375 degrees F. Line a baking tray with parchment paper. Set aside.
Whisk together brown rice flour, cornstarch, potato starch, yeast, xanthan or guar gum, sugar and salt in mixing bowl until well incorporated. Grate frozen margarine with a fine grater into flour mixture. Using whisk attachment mix in the grated pieces of margarine until it looks like coarse meal, such as coarse ground corn meal.
With mixer on low speed drizzle in water in a slow stream. You may not need all the water, so watch the dough near the end of mixing before adding the last bit of water. The dough will be sticky, yet you should be able to handle it. It will be stiffer than most gluten free bread doughs you work with.
Scrape the dough into a pastry bag or into a large gallon-sized freezer bag with a corner snipped off. Pipe long thin bread sticks onto the parchment lined baking tray. I usually make long thin sticks, but you can make curves, swirls, and other fun shapes. Using your fingers, brush olive oil on bread sticks or brush each stick with an egg wash for better sticking power of your toppings and a more golden crust. You can add a topping at this time, such as sesame seeds, salt, poppy seeds, herbs, etc. or leave plain.
Bake for 15 to 20 minutes at 375 degrees F until golden brown. The timing depends on how thick you piped your breadsticks. I like these to be crispy, so bake them a bit longer…