I got a nice char on my tortillas for my photos by putting the tortillas directly over my burners of my gas stove. You have to act quick, so if flames scare you, definitely ask for some help from a friend. I use a silicone tipped tong to move the tortillas around so that the flame does not burn any one spot. Also, keep your flame low. Tortillas cook very fast! You can also try this same method over a gas grill!