Preheat the oven to 410. Scrub your potatoes well if you want to keep the nutrient-rich skin, otherwise peel and rinse them. Cut your potatoes into even, bite-sized chunks. Put the chunks into a large saucepan and cover them with cold water. Add a teaspoon of coarse salt, cover, boil, lower the heat to medium and cook for five minutes. As soon as the water boils, pour the fat into a rimmed baking sheet and heat in the oven.
Drain the potatoes and return them to the saucepan, cover. Holding the lid firmly, shake the pan vigorously - this smushes the edges of the potato chunks and will turn into a crispy crust later.
Take the baking sheet out, pour the potatoes onto it, sprinkle with salt to preference, and stir well, ensuring each chunk is well coated with fat. Bake for 25 to 30 minutes, flipping the potatoes at 12-15 minutes. The potatoes are done when a knife slides through them easily.