Place potatoes in a large pot and fill them with enough cold water to cover them. Boil for 30 minutes or till cooked through and fork tender.
Drain and transfer the potatoes to a large roasting pan or rimmed baking sheet. Arrange in a single layer and press the back of a fork into the center of each potato to “smash” it. Be careful not to crowd the pan. Drizzle or brush the duck fat over the potatoes.
Pop them into the preheated oven and roast till golden brown (approx. 40+ minutes). While hot, Season with truffle salt and freshly cracked black pepper