To really wake up the flavours, toast the rye flour in a large dry pan over a medium heat for 4 minutes, but don’t let it colour. Place in the bowl of a freestanding mixer, then combine with the other flours.,

Dissolve the kansui powder and 1 teaspoon of sea salt in 420ml of cold water. Gradually add the water to the flours, slowly beginning to beat with the dough hook.,

Once incorporated, beat on high for 10 minutes, or until it starts to come together into a grainy dough (it shouldn’t feel sticky). Wrap in clingfilm and place in the fridge to chill for 1 hour.,

When you’re ready to roll, cut off a manageable piece of dough. Cover the rest with a clean damp tea towel while you work, to stop it drying out.,

Using a pasta machine, roll the piece of dough through the widest setting. Fold the edges of the dough back into the middle and roll through again, then work down through the settings until the sheets are 1–2mm thick.,

Switch attachments and cut into 1–2mm-thick noodles, tossing them in cornflour as you go. Repeat with the remaining dough.,

To cook, simply plunge them into a pan of boiling water for 45 seconds, then remove, shaking off any excess water.