Sift the flour into a large bowl. Mix in the salt and a few cracks of black pepper. Create a well in the flour and add the eggs, milk, cold water and mustard. Mix well. Let sit for at least 10 minutes. If there are lumps strain through a fine sieve into a jug for pouring. The consistency should be like whipping cream; if it is too thick, pour in a bit more milk.
Divide the vegetable oil between a 12-tin muffin tray and place in the preheated oven for at least 5 minutes. It is really important that the oil is sizzling hot, almost smoking.
Working quickly, pull the tin out of the oven and fill the muffin holes ¾ full of batter. If you want giant Yorkies, fill them right to the top (you’ll just have less). Remove from the oven and serve immediately.
Bake for 20 minutes. The puds should be golden brown and crispy. If they’re not crispy, they will sink as soon as they come out of the oven.