Preheat oven to Toss the cubed potatoes in the bacon grease on a sheet pan lined with foil (if you've just cooked the bacon, you already have this set up! So easy!). Sprinkle them with salt (and pepper, if you like), then stir and give them another sprinkling so they're generously seasoned. Roast for 25 minutes, then stir and roast for about 10 minutes more, until they are as browned and crispy as you like! Taste and add more salt if needed.