In a medium mixing bowl, combine cassava flour, tapioca starch, xanthan gum, and salt.
Add hot water and melted butter (or other fat) and stir to combine into a shaggy dough.
Use your hands to knead into a smooth dough.
Divide into 9 balls, about 49g each, and gently flatten each ball into a disk.
Roll out the tortillas using a tortilla press or rolling pin.
Preheat a cast-iron or non-stick skillet over medium-high heat.
Cook each tortilla until it starts to bubble up, about 45 seconds, then flip and cook until golden brown.
Transfer each tortilla to a tortilla warmer or a plate covered with kitchen towels to keep them warm.
