One of the kitchen's biggest roadblocks when whipping up a delicious meal is when your pot and lid decide to cling to each other for dear life. Most of the time a stuck lid is a result of temperature and pressure change that cooking creates, but sometimes it's just a case of the lid being a little too tight-fitting in the first place. Whichever is the case for you, there's a way to go about un-sticking your cookware rather easily.
Fixing a Vacuum-Sealed Lid
If the lid becomes stuck, remove the pot from the heat source immediately. Continuing to cook with a stuck lid will only reinforce the vacuum and can warp the lid and pan. Try removing the lid by hand, wearing oven gloves to protect from the heat. If this doesn't work, place a steaming hot towel on the lid for a couple of minutes to raise the outer temperature before trying to remove it again. Repeat as necessary until the lid comes off.
Fixing a Tight-Fitting Lid
To remove a stuck lid because it's tight fitting - not because of a vacuum seal - it's best to cool down the metals first. Doing this will cause the molecules in the pan to contract, making the lid fit less tightly. So place the pot in the freezer for 20 to 30 minutes before trying to remove the lid with your hands. If this doesn't work, take a wooden spoon and tap firmly around the rim of the pan and then the bottom of the pan before trying to remove again. If the lid is still stuck, repeat all steps until it comes off.
- Joy of Cooking; Irma S. Rombauer