When preparing tacos the taco shells are heated in the oven for a few minutes to warm them and then filled with the various taco fillings. However, more often than not you or your family members will want a second helping only to be greeted by a cold taco shell. Keeping your taco shells warm will allow your second or even third helpings to taste just as delicious as the first.
When an oven is turned off it does not suddenly go cold right away. Your oven will gradually loose heat once off but keeps a low heat for a short period of time after it is turned off. You can simply return you heated taco shells to your oven which has just been turned off and they will remain warm.
Another low heat option for keeping them warm, is to leave them in the oven at about 150 degrees Fahrenheit.
Aluminum foil can be used to cover the taco shells to keep them warm. Simply cover them tightly with the shiny side in. This will reflect the heat back on to the taco shells thus retaining the heat for a short period of time. Covering the aluminum foil snugly with a dish towel will keep them warm even longer.
You can also purchase specialty insulated food bags that keep food cold or hot, or simply pop them in a cooler (coolers keep things warm too).
Using the microwave
Another way to keep your taco shells warm is to put the warmed shells in your microwave with the door closed . Do not turn it on. The enclosed area will keep in the heat for enough time to help your self to seconds.
Hot water bath
Place a small bowl or pot (with your taco shells in it) into a larger bowl or pot which has been filled with hot water, cover it. This will keep the shells warm for as long as the water remains hot.