First make the batter. Put the flour into a bowl and whisk it lightly toget rid of any lumps, then add a generous pinch of salt and the dried sage.
Make a well in the middle and add the eggs. Work the eggs into theflour, then gradually add the milk. Leave the batter to stand for an hour.
Preheat the oven to 200°C. Divide the vegetable oil between 2 x 4-hole Yorkshire pudding tins. Put the tins in the oven to heat up for 10 minutes.
Divide the shallots between the tins, put back in the oven and cook for 15 minutes, until the shallots have started to look nice and brown.
Remove the tins from the oven, sprinkle each hole with some rosemary leaves. Pour in the batter around the shallots and rosemary. Bake for a further 20 minutes until the Yorkshire puddings have risen and are a dark golden-brown. Serve hot straight from the oven – with some gravy if you like.