In a large bowl, combine cassava flour, baking soda, cream of tartar, salt, and garlic powder, if using.

Add the oil and knead into the dry ingredients for a minute. The mixture will be dry and crumbly.

Add the coconut milk and knead 2-3 minutes. At first the dough will be wet and sticky, but as the cassava flour absorbs the water it will become drier and more pliable. The texture should be similar to playdough. If it's too sticky, add a bit more cassava flour. If it's too dry, add a bit more liquid.

When the dough becomes pliable, roll it into a log, like a tube of cookie dough. Slice in half through the middle of the log and slice each half into 4 pieces. Roll each piece into a ball.

Place a ball of dough onto a sheet of nonstick aluminum foil. Cover with plastic wrap and roll into a circle about ⅛-inch thick.

Heat a cast iron or nonstick skillet over medium heat. Do not oil the pan. Remove the plastic wrap and turn the dough over onto the skillet, foil side up. Run a spatula over the foil to ensure all edges of the tortilla touch the hot surface. Cook 1-2 minutes or until the foil peels away easily. Flip and cook another 1-2 minutes or until brown spots appear. Transfer to a plate and repeat until all the dough has been cooked. Store any leftovers in the fridge or freezer.