Parcook in the Microwave
Here's how to do it: Just prick a few holes in a few potatoes with a fork, and microwave on high for 3-4 minutes, turning over once. There you go—super-fast par-cooked potatoes.
A potato's cell walls contain pectin, and these pectin chains remain stable when they come into contact with acids. This means that potatoes will remain hard if they are in a dish that has a lot of acid (for example, a dish you've added wine to). Salt is needed to dissolve these pectin chains.
Lumpy mashed potatoes generally mean undercooked potatoes. If you get to this point and you realize you've undercooked your potatoes, just add a little bit of milk or cream and cook the potatoes over a low heat until the lumps begin to soften.
As the potato is cooked its texture becomes softer and 'squishier'. The reason for the change in texture is the rupturing of the cell walls. When they are intact they hold the potato in a rigid shape. They are strong and hard to break just by gently pressing on the potato.
Some food science: Potatoes (like many other starchy plants) contain hemicellulose, a carbohydrate that provides structure to the tuber. It also readily breaks down when boiled in water, lending to the creamy texture we know and love.
Soaking potatoes in water helps remove excess starch. Excess starch can inhibit the potatoes from cooking evenly as well as creating a gummy or sticky texture on the outside of your potatoes. Cold water is used because hot water would react with the starch activating it, making it harder to separate from the potatoes.
Peeled, cubed potatoes cut into small, one-inch pieces should cook in 10 to 12 minutes, once the water reaches a boil. Larger pieces (about 2 inches across) may need longer, around 15 minutes. Medium whole potatoes should boil 20 minutes before they'll be tender.
When cooking potatoes to use in potato salad, add a little vinegar to the water when boiling the potatoes. The vinegar causes the potatoes to form a thin crust, which helps them hold their shape.
For three pounds of potatoes use a 4- to 5-quart pot. Add enough cold water to cover the tops of the potatoes. Add ½ to 1 teaspoon salt to the water. Turn the burner on high and bring water to boiling.
Lumpy mashed potatoes generally indicate undercooked potatoes. If you get to this point and realize you've undercooked your potatoes, just add a little bit of milk or cream, then cook the potatoes over low heat until the lumps begin to soften.
Overcooked mashed potatoes can be rescued too
If you find your mashed potatoes are soupier than normal, it's likely because you overcooked them, Buzzfeed says. Overcooked potatoes aren't always dry and hard, as it's possible to overboil a potato too. When you do so, more water is absorbed by the potato.
Vinegar causes the potatoes to form a thin crust that further helps in retaining their shape. Vinegar increases the acid pH levels of water which further helps the potato just like when you add a little salt to the water while boiling eggs.
Cubed spuds will take around 15 minutes where larger chunks or whole new potatoes will be 20-25 minutes. To check when they are done, pierce the potatoes with the tip of a knife to see how much resistance there is. If it goes in easily, you're done!
It Gives a Firmer Texture
Since soaking potatoes in salt water draws out excess moisture and reduces their ability to absorb oil, it helps them have a firmer texture.
Scrub potato and prick with a fork. Place on a microwave-safe plate. Microwave on full power for 5 minutes. Turn potato over, and microwave until soft, about 5 more minutes.
"Baking soda [what Americans call bicarbonate of soda] breaks down the pectin in the potato and draws starch to the surface. What do you get? Wonderful browning and a crispiness you wouldn't otherwise achieve.”
Vinegar allows you to boil the potatoes the longest and keep them firm but I didn't get the soft outer surface I wanted. (I did get very creamy middles though!) Good, but not quite. Baking soda starts softening the outside right away, long before the middles are cooked.
Why use salt water for soaking potatoes? There's moisture naturally found in potatoes, and moisture is drawn to higher concentrations of salt. (This is a process called osmosis.) So, if you put the potatoes in a salt water bath, that will help draw out some of their moisture, resulting in crispier fries.
In short: Yes! Boiling potatoes with the lid on will make them boil faster because trapping in steam makes it warmer inside your pot and allows more water molecules to evaporate away from your spuds.
Do not cover. (Covering changes the environment in the pot and can make the potatoes turn mushy.) Check the potatoes after 5 minutes. Cubed potatoes will cook more quickly than whole potatoes; smaller potatoes will cook more quickly than larger potatoes.
Potatoes that are still hard after baking haven't had a high enough heat for long enough to soften the starches in the flesh. Cooking for 15 minutes longer or pre-cooking in the microwave should soften the potato. You may need to check your oven temperature if it is faulty.
The soaking, Mr. Nasr said, is the secret to the crisp texture of the fries. It draws out the starch, making them more rigid and less likely to stick together. The cooks fry them twice, first blanching them until slightly limp in peanut oil heated to 325 degrees, and again in 375-degree oil to crisp and brown them.
Soak the potatoes in cold water to remove the excess starch from the outside of the potato. There are a few reasons why you want to remove that starch (it makes the potatoes burn, it keeps them from crisping up, it turns to sugar) but all you really need to remember is to soak them at least one hour.
Don't fry fresh-cut potatoes
Soaking peeled, washed, and cut fries in cold water overnight removes excess potato starch, which prevents fries from sticking together and helps achieve maximum crispness.