Preparation

• To prepare the potatoes: Put the potatoes in a large pot of cold, salted water and bring to a boil over high heat. As soon as a full boil is reached, test for doneness—the potatoes should be tender when pierced with a knife tip. If necessary, continue cooking at a lively simmer over medium heat until done. Immediately drain the potatoes and spread them on paper towels to dry thoroughly.
• To crisp the duck: Heat the oven to 450°F. Line a baking sheet with aluminum foil. Gently wipe off any excess duck fat from the legs. Put the duck legs, skin side up, on the baking sheet. Roast on the top oven rack until the skin is a deep golden brown and very crisp, 20 to 25 min. Check often near the end to prevent burning.
• To crisp the potatoes: While the duck is in the oven, melt 1/4 cup of the duck fat in a heavy 12-inch skillet (cast iron is best) over medium-high heat. When hot, add half of the potatoes and cook, tossing continuously, until deep golden and crisp, about 10 min. Use a slotted spoon to transfer them to paper towels to drain; keep warm. Repeat with the remaining fat and potatoes. When ready to serve, return all the potatoes to the pan, add the garlic and parsley, and sauté until the garlic is just barely golden, about 1 min. Immediately remove them from the heat and season with salt and pepper. Serve hot with the crisp duck legs and a simple salad.