Put the flour in a mixing bowl. [Optional: at this point you can add 1/2 teaspoon of spices, such as ground ginger, curcuma, red pepper, matcha tea, or ground coriander, if you want to flavor or color your dough.]
Pour the boiling water onto the flour and begin mixing with a wooden spoon until you get a rough dough.
Add the salt and cold (room temperature) water. Continue to mix with the wooden spoon until the dough comes together.
Knead the dough about 5 minutes to make it elastic and smooth. If the dough is too sticky, add a little more flour. If the dough is too dry, add a little more water. Try adjusting with only a little flour or water at a time.
Pour the vegetable oil into the mixing bowl or on a hard clean surface. Roll your dough into the oil and continue kneading until the oil becomes incorporated. When you are done, the dough should feel like an ear lobe (soft and smooth). [Optional: at this point you can add some fresh herbs, such as coriander or mint, with 1 tablespoon of water to add flavor].
Optional: Roll the dough in plastic wrap and leave it to sit or put in the refrigerator about 30 minutes. This step is not absolutely necessary but does help to roll out the dough better. You can even leave the dough up to a couple of days in the refrigerator before rolling it out.