The warning "do not heat taco shells in a toaster oven" means that you should not put taco shells directly inside a toaster oven to heat them. Taco shells are typically made from corn or flour and can become very brittle when exposed to high heat.
Toaster ovens are designed to toast or bake various types of food items, but they may not be suitable for heating taco shells due to their delicate nature. When taco shells are exposed to the direct heat of a toaster oven, they can easily break, shatter, or crumble, making them unusable for holding fillings.
Instead, if you want to heat taco shells, it is better to use alternative methods such as:
Oven: Preheat a regular oven to a low temperature (around 250°F or 120°C) and warm the taco shells on a baking sheet for a few minutes until they are just heated through.
Stovetop: Heat the taco shells directly over a gas flame or in a dry skillet on medium heat for a short period until they become warm and pliable.
Microwave: You can also heat taco shells in the microwave for a few seconds, but be cautious not to overheat them, as they may become chewy rather than crispy.
By using these methods, you can warm the taco shells without risking them becoming too brittle or breaking during the heating process. Always follow the manufacturer's instructions and safety guidelines when using any kitchen appliance.