Recipe Instructions:
1 pound starchy potatoes, like Russets (though I used yellow potatoes this most recent time, and it worked ok)
2 teaspoons malt vinegar (or sherry vinegar is also good), plus more to taste
1/4 teaspoon (generous) fine sea salt, plus more to sprinkle on at the end
1 1/2 tablespoons salted butter
Directions
Peel the potatoes, then shred them on the coarse side of a box grater. Squeeze as much liquid as you possibly can from the shredded potatoes. I think the best way to do so is to stick them in a potato ricer and squeeze -- the potatoes will stay in the ricer while the liquid drips out -- but you can also put them in a towel and wring the heck out of them.
Put your shredded potatoes on a plate and microwave them on high for about 2 1/2 minutes. You want them to be hot and start cooking a bit, but they will still be firm and not actually cooked. Take the potatoes out of the microwave and, while they're still warm, sprinkle them with the vinegar and salt and toss.
Add half the butter to a 10-inch skillet over medium-high heat and let the butter brown. Then, add the potatoes and gently press them into an even layer, but try not to smoosh them down. Turn the heat to medium and let them cook, undisturbed, until they have formed a deep brown crust on the bottom, about 8 minutes. (If they start to get brown too fast, turn down the heat. You don't want them to get brown on the outside too quickly because then the inside won't cook enough.) Place a plate directly over the top of the pan and -- using oven-mitted hands -- invert the pan onto the plate so the potato cake gently falls out of the pan and onto the plate.
Return the pan to the heat and add the remaining 3/4 tablespoons butter. Let the butter melt and start to foam, then slide the potatoes off of the plate and back into the pan with the uncooked side down. Cook until the second side is brown and crispy, another 6 or 7 minutes.
Transfer to a serving plate and serve hot, with additional salt and vinegar sprinkled on top, if desired.
