Why You Should Add Vinegar To The Water When Boiling Fries
From thick steakhouse style to crunchy shoestrings and all the other types of fries in between, trying to make the perfect portion of french fries at home can be a minefield. Everyone will tell you something different — whether that's to fry your potatoes in duck fat, to triple cook them, or even to batter them.
Making fries at home is almost always an exercise in imitation: You're only really ever trying to make ones as good as those you might find in a restaurant. Crispy on the outside, soft and fluffy within. You want fries that'll practically snap in two, not just sadly crumple. The shortcut to achieving this is par-cooking them before you fry them (a classic restaurant trick), which involves boiling them for a short time in salted water and then drying them out. But adding a splash of vinegar to the water will make sure your potatoes keep a neat, uniform shape and stay extra crispy once you've fried them. It'll also make for a beautiful, consistent golden brown color — the vinegar will help get rid of any excess sugar in the potatoes before the frying process. Excess sugar might cause certain parts of the fry to over-brown or even burn.
How the vinegar works to perfect your fries
While slowing the breakdown of pectin in the potatoes certainly helps things along when it comes to keeping your fries extra crispy, it's not the only reason they'll get super crispy in the first place. When talking about potatoes, you'll sometimes hear people talk about starch (often without really knowing what they're talking about). There seems to be this misconception that when making fries we want to remove any starch from those spuds before they're fried. But that simply isn't the case! In fact, starch is crucial to making great french fries (it's why the best potatoes to use, Idaho and russet potatoes, are among the starchiest varieties you can buy). It's starch that, once it gets a dunk in some hot oil, develops that shimmering, shattering crust on the outside of our fries.
Boiling potatoes in vinegar can aid in what we really want to do: draw the starch out of the center of the fries (where it will stay waxy and floury) and move it to the outside, where it can crisp up. You'll want to keep a ratio of two tablespoons of vinegar and two tablespoons of salt for every two quarts (1.9 liters) of water for boiling. Nice and easy. Then, it's just a matter of blanching your fries, which you should do in batches, so as not to overcrowd things in the pan. Once they're out of the water, make sure to give them a good dry, and fry away!