Use groundnut, or melted beef dripping for the flavourless oil. Finely slice the red onions. Plus an additional 6 sprigs of the thyme leaves. Sift the plain flour.
- 1 Put 1 tbsp of the oil or dripping in a large frying pan set over a low-medium heat.
- 2 Add the red onion with a pinch of salt and cook, stirring often, for 10 minutes until softened and just starting to colour.
- 3 Add the vinegar and brown sugar, increase the heat and cook for 2-3 minutes, until the onions are sticky.
- 4 Stir in the thyme leaves and set aside.
- 5 Heat the oven to 220°C/200°C fan/gas 7.
- 6 Divide the remaining oil or dripping among the holes of a six-hole muffin tin. Put it in the oven.
- 7 To make the batter, put the flour in a bowl and create a well in the centre.
- 8 Break the eggs into the well and, using a whisk, begin to incorporate them into the flour.
- 9 Add the milk and 120ml water, continuing to whisk to make a lump-free batter.
- 10 Whisk in the mustard and transfer to a jug.
- 11 You now need to work quickly, so have the caramelised onions and thyme sprigs to hand.
- 12 Remove the hot tin from the oven and swiftly divide the batter among the holes (it will splutter when it hits the hot oil).
- 13 Quickly spoon a sixth of the onion mixture into each hole and top with a thyme sprig.
- 14 Cook for 25-30 minutes, until well risen and browned.
- 15 Remove from the tins, season with salt and pepper and serve straightaway.