A number of readers asked for tips on rolling round tortillas. I'll share my thoughts; feel free to leave a comment with your own tips for rolling dough into circles! :)
Start with dough that's been kneaded or patted into a nice little circle shape. Starting with dough that looks like a "cookie" will make it easier to keep it circular.
Place your rolling pin in the center of the dough, and roll to the outside. Work your way around the dough evenly, always starting in the center. Don't roll from one side all the way to the other... unless you want a square or rectangle. ;) If your dough starts looking unlike a circle, give special care to the uneven spots, remembering to roll from the inside out (never out-in).
Use a lightly floured surface. As you can see in the photo above, I was using a tablespoon measure to sprinkle flour on the sides of my tortilla as I rolled it out. Sprinkle lightly, and use your hands (or a pastry brush) to disperse it evenly.
Large patches of flour will ruin the taste of your tortilla! Add flour carefully (in small increments) and frequently (as needed) for best recults.
Turn the tortilla over as often as needed. If the tortilla starts to stick to your surface, it's time to pull it up and add more flour.
Having a good dough helps considerably. To roll a thin tortilla, you will need dough that's not too sticky, because wet or sticky dough is fragile and tears easily. However, dough that's too stiff will be difficult to roll and won't taste as good. I kneaded and added flour to my tortilla dough until it was only the least bit sticky. My tortillas were still very soft (and fragile) until they were cooked, but none of them tore when I lifted or moved them.
Even if you try to follow all of my tips for rolling dough into circles, it still might (okay, probably will!) take some practice. That's okay! I've been rolling dough for years... pretty much ever since I can remember. There are lots of recipes that require rolling (crescent rolls, pie crusts, some pizza crusts and cookies, etc.) and the more attempts you make, the easier it will get! :)