I can never get potatoes boiled just right. They're either over or under cooked. When I think they could be about done, I poke one or two with a knife but then that one splits and cooks faster than others. It also spills the potato juices in the water, and I don't like to do that, which is why I boil whole potatoes and not sliced.

Is there a way to know potatoes have attained just the right level of doneness without poking them with a knife or fork?

  • 1
    It sounds more like you're testing it wrong. Grab a potato with a slotted spoon or a pair of tongs. Take a thin, sharp knife, and stab it about 3/4 of the way through, aligned with the longest axis of the potato. Lift the knife and shake gently. If the potato falls off from its own weight, it's done. If you have to use the spoon or tongs to force the potato off the knife, it needs to cook longer.
    – Joe
    Commented Dec 22, 2014 at 18:54
  • how is that different than what i described how i was doing it?
    – amphibient
    Commented Dec 22, 2014 at 18:55
  • 1
    @amphibent : I didn't know what you qualified as 'poking' (some people slice almost all the way through the potato). Or what size knife you were using. (a heavy chef knife will do much more damage than a paring or boning knife). As I don't have the same issues that you're having, there's either a difference in our testing, or our cooking process.
    – Joe
    Commented Dec 22, 2014 at 19:00
  • @amphibient, boiling whole potatoes might be your problem. If the potato splits after you poke it, it is done or you've sliced it and not poked it. If all of your potatoes aren't getting done at the same time it's due to lack of uniformity of the sizes. Commented Dec 22, 2014 at 22:18
  • 3
    What's wrong with poking? It does not effect the cooking process, or the majority of the potato in any way
    – TFD
    Commented Dec 23, 2014 at 5:06

4 Answers 4


Great question easy fix as I had the same issue. Set aside or add a couple extra chunks or potatoes that is just for testing. When you test a chunk toss it, the test potatoe will be representative of how the other potatoes are cooking, it allows you to puncture without compromising the rest of the batch.


I think the problem is how the potatoes are being poked, and maybe in how they are "boiled".

If done well, then the potatoes should not split and cause trouble with cooking.

To do this correctly, you want to use a very sharp knife with a thin and not too tall of a blade. Typically, I use a paring or boning knife.

  1. Select a potato to be tested. It should be the one of the largest ones being cooked.

  2. Remove the potato to be tested from the water with a pair of tongs.

  3. Line your knife up with the potato so the height of the knife is the longest axis (so there's as much potato above and below the knife as possible).

  4. Stab straight into the potato, about 2/3 to 3/4 of the way into the potato. Do not go all the way through the potato.

  5. Lift the knife, with the potato pointed down, and possibly shake the knife slightly. If the potato comes off, then it's done.

  6. If the potato does not come off, then you want to use the tongs (or a folded over dry paper towel) to grab the potato and pull your knife straight out. You could also slide a fork around the knife to push it off. Do not cut into the potato to release the knife.

This will leave a minimum amount of damage to the potato, and shouldn't cause it to split in half or significantly affect how much starch leaches into the water.

This also assumes that you're only doing this a few times. If you're testing more than 3 times, you may need to wait longer before your first test, or longer in between tests.

If you're cooking extremely small potatoes, then it might be difficult to find a potato that's sufficiently larger than the size of your knife.

You should also be simmering potatoes. A rolling boil is not desired, and the agitation of the potatoes may cause more starch to be released. Once the water comes to a boil, turn the heat down so you're only getting an occasional bubble coming to the surface of the water.


Two hints:

  • The color of the potato peel slightly lightens sometimes even getting transparent if it is a thin one.

  • The skin starts peeling a little from somewhere since the heat tries to escape out of it!!

  • 3
    This is an unreliable test. If you started in hot water and have large potatoes, the outside will be cooked way before the middle of the potato is done.
    – Joe
    Commented Dec 22, 2014 at 18:55
  • Thats why I said hints! I guess just by looking at it even pros will not be able to give a reliable answer!
    – Neels
    Commented Dec 23, 2014 at 7:25

Have the same kind of potatoes always (at least for a couple of weeks at a time) and keep a record of how long you did cook them and how they turned out. If underdone by a bit, lengthen cook time by a bit for the next try. And if 'overdone' shorten the cook time.
Of course you always prepare the potatoes for cooking the same, if you cut, you cut to the same (equal all over) size and if you do not peel, you select your potatoes to all have the same size and general shape.

When you think (or your timer tell you) they are almost done, you use the knife or fork and test a few. They should all be as done as the others.
If they are not, steam them.

For potatoes that do not cook reliably, you can always steam your potatoes for a few minutes (or longer) at the end of the regular cooking time.

Steaming potatoes is done in a pan with a lid, drained so there is almost no water left in the pan, and put it back on a low heat (fire on the lowest setting) and leave it for a few minutes. Depending on the heat settings, you may want to shake the potatoes a few times.
Then you take off the lid and let the potatoes dry, still on low heat and shaken more often.

I have learned this for peeled potatoes, but I guess it will also work for those cooked in the peel.

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