Stir together flour, baking powder, and salt.
Gradually stir in enough of the warm water to form a crumbly dough; work dough with your hands until it holds together.
Turn out onto a board and knead until smooth.
Divide into 12 equal pieces and shape each into a smooth ball.
Cover lightly with plastic wrap and let rest for 15 minutes.
For each tortilla, flatten a ball into a 4- or 5-inch patty; roll into about a 9-inch round, working from center to edges.
Turn tortilla often, stretching dough as you carefully peel it off board.
As each tortilla is shaped, place in a heavy, uncoated wide frying pan or griddle over medium-high heat.
Almost immediately, tiny blisters should appear.
Turn tortilla and immediately press a wide spatula gently but firmly all over top.
Blisters will form over most of surface as you press.
Turn tortilla again and press until blisters turn golden brown; tortilla should remain soft.
If tortilla sticks or scorches, reduce heat.
Stack tortillas as cooked in a folded cloth towel inside a plastic bag; close bag and let tortillas steam.