Preheat the oven to 240°C. Place a 12 cup, or two 6 cup, Yorkshire pudding moulds on a tray. Fill the moulds one third with vegetable oil. Place in the oven for 20 minutes.
Place the flour, eggs, milk, and salt in a deep bowl and blend with a stick blender.
Pass through a fine sieve, into a jug, to remove any lumps. When the oil is ready, open the oven and carefully pour the Yorkshire batter into the moulds, filling to the top.
Close the oven door and do not open it for 25 minutes. Check the puddings to see if they are cooked through. If so, very carefully, remove the puddings and set on the bench.
Remove the puddings from the oil as soon as you can touch them and place on a cooling rack.