Melt a 1/4 tsp. of the coconut oil in a 12" cast iron skillet over medium heat. The frying pan need to be steaming when you cook the tortillas.
Combine the melted coconut oil, cassava flour, tapioca flour, and salt in a large mixing bowl.
Add a 1/2 cup of the water and stir. Continue adding the water 1 tablespoon at a time until the dough forms a ball but is not too sticky.
Roll the dough into a ball and place it on some some parchment paper. Flatten the ball slightly and use a pizza cutter to cut the dough ball into eight pieces (cut it like a pie). Pat out each dough piece on some parchment paper until it is very thin.
At this point you can either pat out each dough piece on some parchment paper until it is a very thin circle or shape each dough piece into a ball and flatten them using a tortilla press. Either way, the tortillas should be no more than 1/8th of an inch thick.
Gently flop each tortilla, one at a time, in the frying pan. Fry for 2 minutes on each side. You may need to add a little bit more coconut oil as you fry each tortilla.
Once fried, place each tortilla on a plate and cover with a towel to serve the tortillas warm. Alternatively you can cool the tortillas on a cooling rack and then just reheat them before you go to serve them.