Put spinach and water in a saucepan and bring to a boil. Simmer 5-10 minutes until spinach is tender and breaks apart easily. Remove from heat. Do not drain. Use a spoon to chop spinach somewhat. It should break up easily. If it doesn't, cook it a little more.
Mix flour, salt, baking powder and a few sprinkles of mixed pepper in a mixing bowl.
Add olive oil and mix well, using your hands if necessary. You don't need to over mix, just try to lightly spread the oil throughout the flour mixture.
Add the cooked spinach with water and stir to blend well. The dough will most likely be sticky. Add flour a little at a time until dough is soft but easy to handle, kneading it in with your hands. It is better if the dough is still a little tacky because it will pick up flour when you roll the tortillas.
Lay the dough out on a floured board and make a tube shape. Cut into 8 equal size pieces. I cut the tube in half, than half each half, than half each quarter to make 8 fairly equal sized pieces. Set aside the pieces.
Working with one piece at a time, roll the dough around in your hand to make a ball. Place on floured board and using a rolling pin, roll it into a flat circle about 9-10 inches in diameter. As you roll, lift edges and check periodically to make sure dough is not sticking to the board. Add flour to the top or bottom as needed to keep dough from sticking. Use as little flour as possible. Too much flour worked into the dough will make it hard.
Heat a 10-inch cast iron griddle on the stove over medium heat. If you prefer, use a paper towel dipped in olive oil and spread over pan lightly. Do not let pan get too hot and smoke. Lay tortilla in pan and cook each side for about 1-2 minutes. Remove from pan and lay flat on a plate. Repeat with each piece of dough, oiling pan as preferred between tortillas. If pan gets too hot during cooking, remove from burner for a few minutes to cool slightly, but pan should be hot when you place the tortilla on the surface.
Do not overcook your tortillas. If your pan is not hot enough, it takes too long to cook the tortilla and it will become tough and lose its softness.
To store, stack tortillas with a piece of waxed paper between each one and seal in plastic bag. Freeze for two weeks or store in fridge for several days. If frozen, let thaw completely at room temperature to avoid breaking when separating. Reheat filled tortilla over a griddle or in the microwave. Do not overheat in microwave as the tortilla will become tough.