Duck Confit with Spicy Pickled Raisins

Using the tip of a knife or the sharp tines of a carving fork, prick duck leg skin all over. Rub with garlic (slices should stick to skin) and season with 1 teaspoon ground pepper and 2 tablespoons salt. Preheat oven to 250 °F. Arrange duck skin side down in a roasting pan or large Dutch oven and add 8 thyme sprigs, 4 chiles (or 1 teaspoon red pepper flakes), and 1/2 cup water. Cover pan with foil or lid and cook until fat is rendered (don't be surprised: there will be lots), about 2 hours. Turn duck skin side up and nestle it into rendered fat. Cover pan and continue to cook until meat is very tender and bones easily wiggle when pulled, 2 –2 1/2 hours longer. Meanwhile, bring vinegar, sugar, mustard seeds, rosemary sprig, remaining thyme sprig, 2 chiles (or 1/2 teaspoons red pepper flakes), 1 teaspoon salt, and 1 cup water to a boil in a medium saucepan. Reduce heat and simmer, stirring occasionally, until sugar is dissolved, about 3 minutes. Mix in raisins, remove from heat, and let cool at least 1 hour. Increase oven temperature to 400 °F. Remove duck from fat and place, skin side up, on a rimmed baking sheet; reserve fat for another use (it will keep 3 weeks in refrigerator or 3 months in freezer; reheat and strain before using). Season duck with cracked pepper and roast until skin is brown and crisp, 30 –35 minutes. Serve duck with pickled raisins. DO AHEAD: Raisins can be pickled 1 week ahead. Cover and chill; bring to room temperature before serving. Duck can be cooked 1 week ahead. Pack duck in fat in an airtight container and chill.