Place potatoes in a large pot of cold, well-salted water.
Bring to a boil and cook 8–10 minutes until just tender on the outside but not fully cooked.
Drain completely and let steam dry for 5 minutes.
Shake the potatoes gently in the pot to rough up the edges.
This creates maximum surface area for crisping.
Preheat oven to 425°F (220°C).
Add duck fat to a heavy roasting pan or cast-iron skillet and place it in the oven for 5–7 minutes until smoking hot.
Carefully add potatoes to the hot duck fat. Toss to coat.
Season with salt, pepper, and herbs if using.
Roast 45–55 minutes, turning every 15–20 minutes, until:
Add garlic during the final 15 minutes so it doesn’t burn.
Transfer to a serving bowl.
Taste and finish with flaky sea salt and fresh herbs if desired.
