By Becky Krystal
Whether you want fluffy or creamy (or gluey, no judgment here), cheesy or garlicky or any other type of spud, here's what you need to know about the different variables.
Type of potato
The potato you use is a primary factor in what your mashed potatoes will be like. Potatoes generally fall into two categories, Harold McGee says in "On Food and Cooking": mealy and waxy, which correspond to high- and low-starch contents.
Mashing method
Starch also plays a role in how mashing affects your, well, mash. The starch granules that absorb water during cooking are just waiting to burst and release starch molecules everywhere. The more vigorously they're broken, the more starch is released, leading to gluey mashed potatoes. If that's your thing, then by all means, bust out the food processor or go to town with your potato masher.
If fluffy is your desired texture, you want to be as gentle as possible with the cooked potatoes, to avoid the release of all that excess starch. Using an electric mixer will release some starch, he says, but not as much as you would with the sharp food processor blade, so the result is on the creamy side.
There's a very low-tech option, too, which is a wooden spoon. Using it to mash the potatoes is less likely to overwork the starch granules than a masher. If you like a little rusticity in your mashed potatoes, with some small pieces amid a relatively smooth mash, the spoon is the way to go.
Fat
Adding fat serves two main purposes in mashed potatoes: texture and flavour. In terms of texture, the fat helps separate and coat the mashed tubers. More fat yields a more luxurious result. At the higher end of the spectrum, there are such options as heavy cream and butter. If you're looking for decadence, this is where you want to be.
Milk will be on the leaner side, not a bad thing if you don't have the stomach for the higher-fat options. I would, though, recommend sticking to full cream or, at the very least, reduced-fat milk. Some sour cream folded into the mix can add fat and tangy flavour.
If you're avoiding or cutting back on dairy, you can use olive oil. Its cleaner flavour can complement rather than overpower the earthiness of the potatoes.
Cheese
Like the other dairy options above, cheese is a multifunctional ingredient, and depending on your taste, you can go as bold or mellow as you want. On the mellower side, you can consider Parmigiano-Reggiano or mild cheddar. Up the ante with smoked Gouda or sharp cheddar or maybe a nutty Gruyere. Want to go really bold? Consider a creamy blue cheese.
Take care not to overwork the potatoes while trying to incorporate cheese, which – you guessed it – can turn them gummy. Fold it in as gently and minimally as you can.
Other ways to flavour
There are plenty of ways to infuse your potatoes with character right from the start. You can add the allium of your choice – onions, garlic, shallots – to the water in which you boil the potatoes. Vinegar in the water will not only impart flavour, it can prevent discolouring of the potatoes, as well.
Fresh herbs folded in or sprinkled at the very end are natural fits. I love the pairing of potatoes and thyme. Parsley or rosemary? Sure, though you'll want to make sure the rosemary is very finely chopped, because of its tougher leaves. Chives and scallions work well for a final flourish of alliums.
Even if you are on a journey to achieving your best mashed potatoes, you don't have to go overboard. Take baby steps as you work to achieve your ideal mash, seeing what works and what doesn't. Even a small change in something as simple as the type of pepper you use is worth trying. While a grind of black pepper is common for a reason, swapping in white pepper may be just enough of a twist to intrigue your guests – and get them going back for more.