In a steamer pot or a large stockpot fitted with a steamer basket, over high heat, add about 3 inches / 7.5 cm water. Place the potatoes in the basket; be sure the basket does not touch the water. Cover the pot, then cook for 15 minutes or until the potatoes are tender when poked with the sharp tip of a knife. Once steamed, lay the potatoes on a tea towel to cool to the point that you can handle them.

Once the potatoes are cool, cut the potatoes lengthwise in half with a sharp knife.

In a large sauté pan over medium-high heat, add the butter and duck fat. Once the butter and duck fat are hot and bubbly, carefully add the potatoes. You will want to be able to lay all the potatoes face down, skin side up in a single layer.

Leave the potatoes to brown and crisp on the first side for 
5 minutes, testing occasionally by peeking at the surface of the potato to check for even cooking. Add the garlic, then flip the potatoes over and cook the skin side for 5 minutes. Toss the potatoes with the warmed garlic and oil right before transferring to a serving plate.

Serve immediately and finish with a sprinkle of fleur de sel.