Mix together the corn flour, salt, one cup of hot water, and the oil together in a bowl and combine.
Add the additional water until you reach the right consistency. What you're going to be looking for is a dough that is wet enough to stick together, but not so sticky that it stays on your hands.
Knead the dough for a minute or so to fully combine the ingredients.
Cover the bowl in order to keep the moisture in the dough - otherwise by the time you're done, it'll be to dry. Take a golf ball sized chunk of dough and either roll flat with a rolling pin or place into a tortilla press. Either option you choose, lay the dough between layers of wax paper or a ziploc bag cut in two. If the dough sticks to the plastic - it's too wet, just add a touch more flour.
Place the tortilla onto a medium-hot skillet, not greased. Cook for 45 seconds to one minute on each side.
Once tortillas are fully cooked, take them off the skillet and place in between a folded towel. This helps keep them supple and warm while you're cooking the rest.
You can use them immediately or store in the refrigerator for a week or so.