Boil a kettle or pan of water.

Put the flour and salt in a medium heatproof bowl and whisk briefly to combine.

Stir in 150ml boiling water, then mix in just enough extra (hot or cold) water to bring the mix together into a dough; it should neither be dry and floury nor sticky, so adjust as necessary.

Knead briefly just until smooth and coming away clean, then cover and leave to rest at room temperature for at least 30 minutes or, preferably, in the fridge for eight-ish hours.

Finely chop the spring onions, white and green parts alike, trimming off the bases and the very tops, and put them in a heatproof bowl with the flour and crushed Sichuan pepper, if using.

Heat the oil for the paste until it’s shimmering, then pour this on to the onions and stir to make a loose paste (if need be, add more oil or flour to get the mix to this consistency).

Divide the dough into four equal parts. Put three of the pieces of dough back under cover.

On a lightly floured surface, roll out the fourth piece of dough into as thin a rectangle as possible, towards the end stretching it with your fingers.

Brush about a quarter of the spring onion paste all over the top, leaving a small border around the edge.

Tightly roll one of the long ends of the dough rectangle into the middle, then repeat from the other side, so the two 'sausages' meet in the centre.

Press together the ends to seal, stretch slightly, then form into an S shape.

Roll up from one end into a spiral as far as the middle, then repeat on the opposite side from the other end, so the two meet in adjacent spirals.

Fold over and stack these spirals one on top of the other, then leave to rest while you repeat with the remaining pieces of dough and filling.

Starting with the first pancake, flatten it slightly, then roll it out into a thin disc.

Set a nonstick or well-seasoned frying pan over a medium heat, and just cover the base with oil.

Once it’s very hot, add the pancake, then cover the pan and turn down the heat to medium-low.

Leave to cook for about three minutes, until golden underneath, then turn over and repeat.

Uncover, continue to cook until the pancake is browned to your liking, then drain on kitchen paper and repeat with the remaining pancakes, adding more oil as required.

In a small bowl, whisk all the ingredients for the dipping sauce, if using.

Cut the pancakes into wedges (if serving as a snack) and serve with the sauce alongside for dipping.