Hot and sour potato shreds

Step 1: Drop the cut 1 ⅛ lb waxy or all-rounder potatoes into a bowl of 4 ¼ cups cold water and swish it with your hand. Drain, refill and repeat 2–3 times until the water stays clear instead of milky.

Step 2: Drain the potato well and spread it on a clean tea towel to dry. Wet shreds splutter in hot oil and steam instead of frying.

Step 3: Heat 2 tbsp vegetable oil in a wok over a medium heat. Add ½ tsp Sichuan peppercorns and 6 dried red chillies and stir for about 20 seconds, until the chillies darken to deep red and the oil smells toasty. Pull the wok off the heat if they start to blacken; burnt chilli tastes bitter.

Step 4: Turn the heat to high, add 2 cloves garlic and, a few seconds later, the potato and ½ green pepper. Toss constantly for 2 minutes. The shreds are ready when they turn translucent at the edges but still snap when you bite one.

Step 5: Common mistake: cooking until soft. Take it no further: splash 2 tbsp rice vinegar or Chinkiang black vinegar down the hot side of the wok so it sizzles and its sharp smell rises, then add ¾ tsp salt and ½ tsp sugar and toss for 20 seconds.

Step 6: Throw in 1 spring onion, give two more tosses and tip onto a plate straight away, so the heat of the wok doesn't keep cooking it. For the Shanxi version, use aged vinegar, halve the chilli and leave out the Sichuan pepper.