Alsace Onion Tart (Tarte à l’Oignon)

Name: Alsace Onion Tart (Tarte à l’Oignon)
Prep time: 1 h
Cook time: 45 min
Total time: 1 h 45 min
Cuisine: French
Ingredients: 2 cups all-purpose flour, plus more for dusting; ¾ teaspoon salt; 1-1/2 sticks of cold butter, cut into cubes; 5 tablespoons ice water; 1 teaspoon cider vinegar; 4 bacon slices (1/4 lb), cut crosswise into ⅛- to 1/16-inch-wide strips; 2 lb onions, halved lengthwise and very thinly sliced crosswise (10 cups); 1¼ teaspoons salt; 1 teaspoon black pepper; 1 cup heavy cream; 4 extra large eggs; 2 egg yolkes; ½ teaspoon freshly grated nutmeg; 2 tablespoons minced fresh thyme