Step 1

Wash the potatoes, leaving the skins on. Use the large side of a box grater or a food processor large grating blade to grate the potatoes. Place the grated potatoes into a large bowl and fill it with cold water. Tip the bowl to drain off starchy water, then fill it again. Stir the potatoes to release starches soak them for 2 minutes.

Step 2

Drain the grated potatoes and squeeze out any excess water. Transfer them to a clean, dry towel. Wring the potatoes in the towel to remove as much liquid as possible. Place the potatoes in a bowl and stir with the kosher salt and lots of fresh ground black pepper.

Step 3

In a large, heavy skillet (cast iron is best), heat the olive oil and butter over medium high heat. Add the potatoes in an even layer and press them down gently with a spatula. Cook for 4 to 5 minutes without stirring until browned on the bottom. Flip and cook additional 6 to 7 minutes until cooked through, stirring and flipping occasionally to ensure all parts are browned. If necessary, drizzle with a little olive oil when you are stirring to continue the crisping. Taste and add additional salt if necessary: serve immediately.