Mustard Yorkshire puddings

Method

1. Preheat the oven to 220°C/fan200°C/gas 7. Sift the flour and salt into a bowl and make a well in the centre. In another bowl, beat the eggs with the mustard, then gradually mix into the flour with the milk and sparkling water to give a smooth batter.
2. Add a little fat from the cooked beef (or some olive oil) to each hole of a deep 12-hole muffin tray. Pop in the oven for 5 minutes, or until smoking. Remove from the oven, pour in enough batter to fill the holes three-quarters full and bake for 25 minutes, until cooked through, puffed up and golden. Serve with the thyme-roasted beef and other side dishes.