Preheat your oven to 400°F (200°C).
Dice the Yukon gold potato into 1/2-inch cubes and place them on a parchment-lined baking sheet.
Toss the potatoes with the duck fat, minced garlic, chopped rosemary, chopped thyme, sea salt, and black pepper.
Roast the potatoes for 20-25 minutes, tossing once halfway through, until they are golden brown and tender.
While the potatoes roast, place the duck leg confit skin-side down in a cold oven-safe skillet.
Turn the heat to medium and sear for 5-8 minutes without moving the leg until the skin is golden and extremely crispy.
Carefully flip the duck leg and transfer the skillet to the oven for the final 5 minutes of the potato roasting time to heat through.
In a small bowl, toss the fresh arugula with the lemon juice for a bright, acidic contrast.
Plate the crispy duck leg alongside the herb-roasted potatoes and the light arugula salad.