Cooking science/techniques - pot lids (REPOST as per Chowhound Team)
I am learning to cook and this may be trivial...but...
1)What is the purpose of using a pot lid or not during cooking? Please give an example of things you would cook with the pot lid-less and lid-ded?
2)Also, what is the purpose of the steam venting hole in the pot lid. Does it relate to your answer to (1) above?
Well, a lid will keep steam inside the pot and make whatever you're cooking more moist. If you want to dry out the dish (or thicken it up) take the lid off (like reducing a sauce or soup or stew.) I cook oatmeal without a lid but I watch it like a hawk, and stir often.
I don't have any lids with steam vents, and if want just a little steam to come out, i just put the cover on slightly ajar.
Cook Oatmeal with the lid on. Keeps the moisture in and helps it cook faster.
Cook green vegetables with the lid off. This allows the gasses that turn them that yucky brown to escape.
Anything that will be rapidly boiling - potatoes, etc...I leave the lid on until it boils and then take it off so it doesn't overflow.
Don't worry, as you learn, you will develop a 'sense' for these things...good rule of thumb already stated here is 'lid on retains moisture' and 'lid off evaporates' Once you decide which you want to do, you will know the answer :-)
>>"1)What is the purpose of using a pot lid or not during cooking? Please give an example of things you would cook with the pot lid-less and lid-ded?"
Cooking with a pot lid keeps the liquid from evaporating too fast. It also helps in heat management. Less heat (on the burners) to keep the liquid simmering or boiling.
Long cooking dishes usually call for lids partially covered. Think of black bean soup, which you may be cooking for 4 hours. Lentil soup is another.
OTOH, if you are making a sauce or gravy, you will want to concentrate flavor. Off with lid. Stocks. You want some evaporation but need to keep it at a gentle simmer. It would be hard to keep it (or see it) at a simmer with a lid on.
Pasta is an interesting case. You are only boiling for 12 minutes max in a lot of water. No worries about running dry. But you want the water to come back to a boil as quickly as possible after you put the pasta in. So you lid it, watch it, and unlid it as soon as it starts to boil--else you'll have a boil over.
Venting hole is lid mostly covered.