When my mom makes okra, she adds okra in the pan with all the masala. When she covers the pan with a plate for the okra to cook, she pours some water over the plate. She says it helps it to cook faster or something, but she doesn't know any scientific reason. It's more like advice passed down from others. Is there any reason we should?
The reason she puts water on the plate is to weigh it down so it seals better. Weight will press the plate down, less steam will escape so the okra will cook at a slightly higher temperature. It works, but it's not as good as a tight fitting lid on a good pot.
I guess it is to protect the plate which is used to cover it. The water will absorb the direct heat and protects the plate from cracking.
As a chemist a "lid" on a pot would not raise the boiling point of the water. You'd need a pressure cooker to do that.
A "lid" would help keep steam inside the pot when you cook something like dumplings which are above the fluid level. Having any sort of unpressurized "lid" on the pot would also allow the steam from the pan to condense and drip back in the pot. This could help keep the pan from boiling dry.
So "faster" depends on the fluid level to the okra pods.
To me the extra weight of the water would help keep a light plate from "bumping" up and down on the top edge of the pot. Not so much a "better" seal from a pressure point of view but a less noisy one. Moment of inertia thing.
Yes, multi-purpose. To trap steam and distribute heat inside like a pressure cooker, yet protecting itself. A pressure cooker has a thick wall, but a thin top cover can otherwise get overheated.
The reason is to keep the okra from cooking to fast and cooks evenly. The plate and water keep it from getting too hot too fast. Okra is a fibrous plant seed pod and needs extra time and would burn other wise.