Heat a wok until it just starts smoking. Add 3 tablespoons of peanut oil and stir-fry the chillies and Sichuan pepper over medium heat until fragrant and the chillies are just beginning to brown — don’t blacken them. Immediately remove from the wok and allow to cool, then chop finely.
Reheat the wok, add 3 tablespoons of peanut oil and stir-fry the celery, leek and spring onion for 2 minutes, adding some sea salt to taste. Tip the vegetables straight into a serving bowl and sprinkle the bean sprouts on top.
Heat another 3 tablespoons of peanut oil in the wok. Add the chilli bean paste and stir-fry for 30 seconds until the oil is fragrant. Add the stock and the dark soy sauce and, when boiling, fold in the beef slices. Wait for the sauce to return to the boil and stir. Simmer for a minute and pour over the vegetables.
Wipe the wok and return to the heat. Heat until almost smoking and add the rest of the peanut oil. Add the chopped chillies and stir quickly, pour over the beef and send your sizzling beef to the table.