4 large eggs (200g; 7 ounces)
150g all-purpose flour (5.25 ounces; about 1 cup plus 2 teaspoons)
175g whole milk (6 ounces; 3/4 cup) (see note above)
25g water (.85 ounces; 1 tablespoon plus 2 teaspoons) (see note above)
2g kosher salt (about 1/2 teaspoon)
100ml beef drippings, lard, shortening, or vegetable oil (about 1/2 cup)
Combine eggs, flour, milk, water, and salt in a medium bowl and whisk until a smooth batter is formed. Let batter rest at room temperature for at least 30 minutes. Alternatively, for best results, transfer to an airtight container and refrigerate batter overnight or for up to 3 days. Remove from refrigerator while you preheat the oven.
Adjust oven rack to center position and preheat oven to 450°F (230°C). Divide drippings (or other fat) evenly between two 8-inch cast iron or oven-safe non-stick skillets, two 6-well popover tins (see note above), one 12-well standard muffin tin, or one 24-well mini muffin tin. Preheat in the oven until the fat is smoking hot, about 10 minutes.
Transfer the pans or tins to a heat-proof surface (such as an aluminum baking sheet on your stovetop), and divide the batter evenly between every well (or between the two pans if using pans). The wells should be filled between 1/2 and 3/4 of the way (if using pans, they should be filled about 1/4 of the way). Immediately return to oven. Bake until the yorkshire puddings have just about quadrupled in volume, are deep brown all over, crisp to the touch, and sound hollow when tapped. Smaller ones will take about 15 minutes, popover- or skillet-sized ones will take around 25 minutes.
Serve immediately, or cool completely, transfer to a zipper-lock freezer bag, and freeze for up to 3 months. Reheat in a hot toaster oven before serving.