Marinate the beef with salt, 1/2 ginger juice and 1/2 cornflour slurry for 10 minutes.
Make the sauce by mixing together the remaining ginger juice, vinegar, MSG, salt, sugar, cornflour slurry and stock.
Heat the oil in a wok until hot over high heat. Stir-fry the beef for about 1 minute. Add the garlic, pickled chillies, Sichuan peppercorns and onions stir fry.
Stir in the white pepper, oyster sauce and sauce mixture. Stir until the sauce has thickened. Serve.
Sichuan peppercorns, monosodium glutamate and Chinese black vinegar can be purchased in Chinese/Oriental speciality shops.
To make ginger juice. Finely choped fresh ginger, place into a fine mesh cloth and squeeze out the juice.