Small handful fresh rosemary leaves, finely chopped
3 medium cloves garlic, minced
Freshly ground black pepper
Small handful fresh parsley leaves, minced
Instructions
Preheat the oven to 450°F (230°C), or 400°F (200°C) if using convection.
Bring a large pot of water to a boil. Season generously with kosher salt, add the baking soda and potatoes, and return to a boil. Reduce to a simmer and cook until the potatoes are tender and offer little resistance when pierced.
Meanwhile, combine the fat with rosemary and garlic in a small saucepan. Cook over medium heat, stirring and shaking the pan frequently, until the garlic just begins to turn golden. Strain the infused fat into a large bowl and reserve the garlic and rosemary.
Drain the cooked potatoes and let them rest briefly so excess moisture evaporates. Transfer them to the bowl with the infused fat, season with salt and pepper, and toss vigorously until a thick, mashed-potato-like coating forms on their surfaces.
Spread the potatoes on a large rimmed baking sheet in a single layer with space between the pieces. Roast for about 20 minutes without moving them.
Turn the potatoes and continue roasting, turning and shaking occasionally, until they are deeply browned and crisp on all sides, about 30 to 40 minutes longer.
Transfer the potatoes to a large bowl. Add the reserved garlic and rosemary along with the parsley, toss to coat, adjust seasoning, and serve immediately.
Notes
Russet potatoes produce especially crisp exteriors, while Yukon Gold potatoes offer a creamier texture and richer flavor.
Baking soda raises the alkalinity of the cooking water, helping break down the potato surfaces so they become exceptionally crisp during roasting.
For the best browning, avoid overcrowding the baking sheet.
Duck, goose, or beef fat can be used instead of olive oil for a richer flavor.