How do I prevent the edges of the aluminum foil from curling up when cooking in it?

To prevent the edges of aluminum foil from curling up during cooking, you can dampen the edges with a little water or cooking oil. This helps to weigh down the foil and keep it flat. Additionally, you can fold the edges inward to create a small rim, which can help contain the food and prevent the foil from lifting. Another method is to use a heavier object, such as a ceramic dish or a small pan, to press down on the foil, keeping it in place. Ensure that the object is heat-resistant and won't react with the foil. These techniques can help maintain the integrity of your foil and keep it from curling up during the cooking process.