Preheat oven to 250F. Peel potatoes and slice very thin with a mandolin slicer. Toss in a bowl with 1/2 cup olive oil (or fat of choice) and 1 1/2 tsp salt (plus more, as needed).
Layer potatoes in a tight stack in a parchment-lined loaf pan. Cover with another sheet of parchment and bake for 3 hours.
Remove from oven, weigh down the top of the parchment-topped potatoes evenly with cans or other heavy kitchen objects. Refrigerate for 12 hours (I allow this part to take place overnight). Remove weights and parchment and carefully invert potatoes onto a cutting board.
Cut the potatoes into even 1" stacks and then cut all of those evenly in half.
Heat oil in a dutch oven or pot with high walls over medium high heat. When the heat reaches about 375F, carefully drop in potatoes one at a time until a few are in the pot. Fry, turning occasionally, until potatoes are golden all over but not burnt - 3-5 minutes (keep an eye on them!).
Remove from oil, hit them with a good sprinkle of salt and allow them to cool on a rack set over a baking sheet. Repeat process with remaining potatoes.
While your potatoes are frying, prepare your steak of choice. I chose a filet and salted it all over and allowed it to sit at room temperature for 40 minutes before cooking it. I season with pepper and then sear it off for about 6-7 minutes, flipping occasionally, until I've reached a nice medium rare.
Slice up and serve the steak along side the potato stacks with dipping sauce of choice and perhaps a drizzle of chili crisp, herbed butter or chimichurri on your steak.