Preheat the oven:
Preheat your oven to 425°F (220°C). Place a 12-cup muffin tin in the oven to heat up as it preheats.

Make the batter:
In a bowl, whisk together the flour, milk, eggs, and salt until the batter is smooth. Let it rest for about 10 minutes while the oven heats up.

Prepare the tin:
Remove the hot muffin tin from the oven and carefully add 1 teaspoon of oil to each muffin cup. Return the tin to the oven for 5 minutes, allowing the oil to heat until it starts to shimmer.

Pour the batter:
Quickly pour the rested batter into each muffin cup, filling each about halfway. Immediately return the tin to the oven.

Bake the puddings:
Bake for 20-25 minutes, or until the Yorkshire puddings have puffed up and turned golden brown. Do not open the oven door during baking to ensure they puff up properly.

Serve:
Once baked, remove the Yorkshire puddings from the tin and serve them hot with your favorite Christmas roast.