To Prep
In a mixing bowl, combine the marinade ingredients together and add in the beef. Mix and set aside for at least 10 minutes to marinate.
To Cook
In a wok, cook the beef without oil for about a minute before transferring on to another plate to cool.
Add oil to the wok and heat over a high heat before frying the onions and the green peppers for 30 seconds.
After this, add in the garlic and the fermented black beans and continue to fry for another 30 seconds.
Return the beef strips back in to the wok and fry for 30 more seconds before adding in 2 tbsp of water, the sugar and salt and mix in.
Finally, mix together the cornflour mixture ingredients and slowly pour it in a little at a time. Mix the sauce well before adding soy sauce and simmering for until the sauce thickens.
Once the sauce has thickened, remove the wok from the heat and serve!
