Kosher salt • baking soda • (about 2 kg) russet or Yukon Gold potatoes, peeled and cut into quarters, sixths, or eighths, depending on size (see note) • extra-virgin olive oil, duck fat, goose fat, or beef fat • Small handful picked fresh rosemary leaves, finely chopped • medium cloves garlic, minced • Freshly ground black pepper • Small handful fresh parsley leaves, minced