Can stew with just beef and onions sit overnight in a cast iron pot?

It's generally not recommended to leave a beef and onion stew in a cast iron pot overnight. Here's why:

* Bacteria growth: Leaving food at room temperature for extended periods (more than 2 hours) allows bacteria to grow, which can make you sick.

* Metal leaching: While cast iron is generally safe, leaving acidic foods (like stew) in it for a long time can cause some iron to leach into the food, potentially affecting its taste and altering the nutritional content.

* Potential for rusting: If the stew is not completely covered with liquid, the exposed cast iron surface could be prone to rusting.

What to do instead:

* Refrigerate the stew: After cooling the stew to room temperature, transfer it to an airtight container and refrigerate for up to 4 days.

* Reheat thoroughly: When reheating, make sure the stew reaches a temperature of at least 165°F (74°C) to kill any bacteria.

Note: If you absolutely need to leave the stew in the cast iron pot overnight, you can try to store it in the refrigerator with the lid on. However, it's still recommended to transfer it to an airtight container for better safety.