In a large pot with fitted lid of boiling water, add 1 tablespoon salt and the potatoes. Boil for 10 minutes.
Drain and return to lidded pot. Add 1 teaspoon salt, shake potatoes in pot with lid on to rough up the outside of the potatoes for 5 to 6 shakes.
Add duck fat, rosemary, and a good pinch of pepper. Carefully fold in until potatoes are well coated.
Add potatoes into the air fryer basket and cook for 15 minutes at 340°F.
Shake air fryer basket to toss potatoes, increase heat to 400°F and cook an additional 5 minutes until potatoes are crisp and brown. Fork test to be sure they are cooked through and fluffy on the inside.
For extra, extra crispy potatoes, heat 2 tablespoons of duck fat in a shallow metal roasting pan in 400° oven for 5 minutes until shimmering. Using tongs, carefully add the air fried potatoes into hot duck fat, roast 5 minutes, turn and roast additional 5 minutes. Transfer and drain on paper towel-lined plate.
Sprinkle with sea salt and fresh herbs and serve immediately.
