Steam-heating a Large Amount of Tortillas:
Set up a rack in a large roasting pan, pour in about 1/2 inch of water and cover the rack with a heavy (preferably terrycloth) kitchen towel. Don't let it shouldn’t touch the water or it will act as a wick, soaking the bottom layer of tortillas. Divide your tortillas into stacks of 10 or 12 over the cloth, cover with a second cloth, cover the pot tightly and bring to a boil over medium-high heat. Time 1 minute, (IMPORTANT!!!) turn off the heat and let stand 15 minutes without opening the lid.
You may put the roasting pan in a low oven (not hotter than 200 degrees) and keep the tortillas warm for about an hour or so. Plan to heat a few more tortillas that you’ll need, since the top and bottom ones reheated by this method tend to get so soft they fall apart.

Other Reheating Methods: Factory-made tortillas packaged in the paper wrappers (they may have a thin plastic-like coating inside) may be successfully reheated in a microwave oven: make a tiny hole in the package (to let steam escape), then microwave in the package for 30 to 60 seconds (depending on the power of your oven) on high. Wrap in a heavy cloth and let stand a few minutes before serving.