You need one of these. Seriously, you NEED one of these! Although it looks like something from the inventory of the Spanish Inquisition, it's probably the most effective kitchen gadget ever invented. It's a Potato Ricer.
It's called a Ricer because when you process potatoes with it, the finished product comes out in little "grains" a bit like rice. It works just like a Garlic-press. It has a removable metal bowl whose base has multiple small-diameter perforations.
This is THE device for making the perfect mashed potato. You boil your potatoes in the usual way, and when they are cooked you spoon them individually (perhaps 2 at a time if they are small ones)into the metal bowl of the Ricer and squish them through the perforations. The long handles and robust geared mechanism mean that remarkably little effort is required. It takes a bit longer than usual to make a batch of mash, but it is definitely worth the extra time, because you get the smoothest mash imaginable. Guaranteed no lumps!
This one of ours is a professional-standard one, and is very strongly built. The only other one we have had failed dismally. The handles were so flimsy that they bent irretrievably the first time we used the device!
This one is called a "Chef'n Freshforce Potato Ricer". It is priced at about £25 - £30, depending on where you shop. You can currently get it from Amazon for £25.16. Well worth the money, in my opinion.
You can also use the Ricer for processing Celeriac, Swede, Parsnips etc, though I must add that due to the fibrous nature of those vegetables, it is harder work to pass them through the device.
We have quite a few gadgets in our kitchen, but they have to be good if they are to be retained. Some things get used once and quickly discarded (e.g. a Spiralizer), but if something is good, we use it again and again. We still have a garlic-crusher that was a wedding present (we're just coming up to our 39th anniversary)! I also cite as an example of a worthwhile gadget the "Mouli-Legumes" thing that we use for crushing and sieving tomatoes. It is only used at certain times of the year, but we wouldn't want to be without it these days.
What's your favourite kitchen gadget?