I have a 4 hol yorkshire oudding tin, can use a 12 hole cake tin but I find they stick a bit.
I mix up 1 egg, add about 70g plain flour, mix well then make it up to 1/2 a pint with milk. Mix well.
Make sure oven is about 200+ put little splosh of oil in tin then put in oven for about 20 mins till BOILING. Pour in batter, should sizzle nicely. Mine are usually done in 18 mins, may take more. If too much oil in tins, they are a bit soggy in the middle.
Agree re very hot oven and very hot fat. White fat (eg trex) is fab for YP. Always use plain flour. Then, instead of using traditional method & ingredients try nigella's recipe (ignore the beef and eggplant/pea bit!) I use half those amounts for family of 4. She uses twice the amount of egg to the traditional recipe and a different method. Never failed for me.
google the jamie oliver recipe, that's the one I do and it's idiot proof......believe me it's embrassing to say I'm from yorkshire and my parents have shown me for years how to make proper ones and still can't until i found the JO recipe and they love it.