In a large bowl, mix together the flour and salt.
Add the cubed butter and use a fork to work it into the flour until the mixture resembles a coarse meal.
Add the water gradually, mixing and kneading gently until a smooth dough forms and all the flour is incorporated.
Divide the dough into 20 equal pieces and roll each into a ball. Cover with a damp towel and let rest for at least 30 minutes.
Preheat a cast-iron skillet over medium-high heat.
On a lightly floured surface, flatten and roll each dough ball into a thin round, about 6 inches in diameter.
Place a tortilla onto the hot skillet and cook for about 30 seconds per side, until bubbles form and light golden spots appear.
Remove and stack the cooked tortillas, covering them with a clean towel to keep warm.
Serve immediately.