Preheat your oven to 425°F (220°C). Add duck fat to a roasting pan and place it in the oven to heat up.

Wash the yellow potatoes and cut them into halves for small ones, quarters for medium ones, and keep large ones whole.

In a large pot, add the cut potatoes to cold water with a pinch of kosher salt. Boil for 10-12 minutes until just tender.

Drain the potatoes in a colander and let them steam dry for 5 minutes.

Return the dried potatoes to the pot, sprinkle in baking soda, salt, pepper, minced garlic, and rosemary. Drizzle olive oil and toss to coat.

Spread the potatoes in a single layer in the roasting pan and roast for 45-60 minutes, flipping halfway through.

Once golden, remove from the oven and sprinkle with flaky sea salt before serving warm.