The technique — it's an open secret among those who have the most at stake in the optimization of food.
Retail food professionals like chefs and caterers know it, because flavor is money. The technique is known to home economists who make it their business to satisfy demanding palates on the cheap. I learned the technique from a farmer, who learned it from a farmer — farmers who make it their pleasure to justly celebrate the terroir of their own topsoil. I can only hope my Ukrainian ancestors knew it, as they ate a lot of potatoes.
Given how perfectly the potatoes — and some other roots — come out when the technique is applied, how easy it is and how many purport to love roasted roots, it’s a wonder that more home cooks don’t use it. But the reason is simple: very few recipes suggest it.
Google roasted roots or roasted potatoes, and you will find links to recipes from the likes of Epicurious, Genius Kitchen, Food Network, Eating Well and the New York Times, not a single one of which mentions to soak the damn potatoes in water, after cutting and before cooking. The technique also works for yams, sweet potatoes and squash, an honorary root if there ever was one.
The technique results in what we all want in a roasted potato, a flaky golden exterior, and a puffy warm explosion inside. Kind of like a tater tot made from an actual chunk of potato.
While you may not find this quick and lifestyle-changing technique in your favorite recipe book, you will probably find advice to stir, or solve problems by adding extra oil. These moves may result in roots that are brown and crispy on the outsides, but are less pleasing when bitten into. The interiors may be gooey, or chewy, or tough.
The soaking — or parboiling as some choose to do — washes away excess starch. That allows the cut faces to develop new skins, which fuse together around each piece of potato to create a seal which, when heated, holds in the heat and steam, causing each potato piece to puff out like a little balloon.
Proponents of the parboil, rather than pre-soak, such as Kenji Lopez-Alt of Serious Eats (one of the few enlightened corners of the web), tout that it creates better exterior texture, especially if the potatoes are roughed up a bit with stirring after the parboil, which creates a starchy foam on the exterior which browns into a cross between a Pringle potato chip and the skin of a perfect piece of fried chicken.
But for all of the gains the parboil makes on the outside, the insides don’t compare. That starchy foam disrupts the formation of an oven skin around the potatoes, which don’t blow up like balloons.
So cooks must choose between perfect insides or perfect skins. Most would probably choose the crust with nooks and crannies that break into a million golden pieces when you bite, even if the inside has lost a certain integrity. That’s the easy choice, at least on paper. But once you’ve tasted the results of soaking, it’s tough to give it up.
When I have a big assortment of roots, not just potatoes, I parboil, followed by a rough stir. This creates a creamed mix of all of the roots that in turn coats them all, putting a bit of each root into every bite. This mishmashed earthy veneer absorbs the oil and spices, coats the pieces and cooks into a tasty crust.
But if I'm doing potatoes alone, especially purples, golds and russets, I do a pre-soak in cold water. The recipe below details the parboiling of myriad roots, and also explains how to do a simple soak.
Roots that rock
Each type of root is different. Within the potato category alone, starchy ones like russets or Yukon golds will outperform waxy types, like fingerlings or reds. My favorite potatoes to use, in both soaking and parboiling contexts, are purples, the starchiest of all. When soaked, they blow up the fattest, coming closest to looking like an uncut potato, like an ankle so swollen you can't see the bones.
When it comes to choosing roots, the earth is the limit. Use whatever you like, though be advised some can be problematic. I avoid roots that are too watery, like onion, or roots that are bitter, like garlic or rutabaga, as the bitterness can intensify with cooking. I avoid red beets, which will stain the entire tray, even if you are careful not to stir. For squash, the honorary root, I like 'em starchy, like my spuds. Kabocha and Sunshine and Buttercup varieties are my favorites. Carrots, yams, sweet potato, parsnip and celeriac are all good choices, although many of these will stay moist inside and won't crisp up. Ditto for kohlrabi, another honorary root.
2 pounds roots, peeled and cut to roughly the same size
3 tablespoons salt
1 tablespoon garlic powder
1 tablespoon smoked paprika
1 tablespoon black pepper
1-2 teaspoon ground cumin
4 tablespoons olive oil
Optional: fresh garlic and butter for dressing; ketchup, mayo and hot chile flakes too.
Add 2 tablespoons salt to a gallon of water and bring to a boil. Bring to a boil and add the roots. When the water returns to a boil, cook for 10 minutes. Drain the roots, and allow to cool. Preheat the oven to 425 degrees, along with a tray.
(If you are doing only potatoes, cut them and soak in a pot of cold water, with 2 tablespoons of salt, for 30 minutes. Proceed.)
Mix the cumin, black pepper, garlic powder and 1 tablespoon salt, and add two tablespoons of this mixture to the roots. Stir them around roughly, to help disintegrate the soft, starchy exteriors. Add the olive oil and stir again.
(Drain the soaked potatoes, air-dry for 10 minutes, and toss in the oil and then spices, as above.)
Spread the roots upon the hot tray and hear them sizzle. Put as many pieces on the tray as possible without letting any of them touch.
Bake for 30 minutes. Remove the tray and inspect. Turn each piece so a different side faces down, and bake again, removing pieces periodically and testing them, until you decide they are done. (The soaked potatoes will whistle like 100 little pinpricked blimps.)
Serve with some kind of tangy sauce or dip. I like a mix of ketchup and mayo. If I really want to impress, I melt some butter and a pan and sauté fresh garlic and green herbs, like parsley, sage, rosemary and/or thyme. Toss the roots in the garlic herb butter and serve.