Step 1

Scrub the potatoes but don't peel them. Line a bowl with a flour sack towel or some cheesecloth. Grate the potatoes onto the cloth, then gather the ends of the cloth and squeeze the liquid from the potatoes into the bowl. Set the potatoes and cloth aside, and let the potato liquid in the bowl sit until the starch settles, 10 to 20 minutes. You should have 8 to 10 cups of grated potatoes.

Step 2

Carefully drain the water from the starch in the bottom of the bowl, reserving the starch and discarding the water. Add the grated potatoes to the bowl, a small handful of flour (maybe two tablespoons or so), and a generous pinch of salt, and toss to coat the potatoes.

Step 3

Melt a generous blob of butter in a large cast-iron skillet (10 to 12 inches) over medium heat. Add the potato mixture and pat it down into an even layer. It should be 3/4 to 1 inch thick. Cook over medium heat, letting it turn a nice golden brown. Brown one side before turning it over. Don't increase the heat above medium to rush it, but do peek occasionally to make certain the potatoes aren't browning too quickly. You want the outside to turn pale brown by the time the inside is slowly becoming tender. Flip the boxty. Cook the pan boxty on the other side until crisp and golden on the outside, tender and creamy on the inside, about 40 minutes total, depending on the heat and the size of your skillet. Again, be patient and don't crank the heat or the outside will scorch while the inside remains underdone.

Step 4

Cut the boxty into 4 wedges and serve it straight from the skillet.