Combine beef strips with beef marinade, mix well. Marinate for at least 15 minutes or up to 24 hours.
When ready to cook, add 1 tablespoon of oil and ginger in a large non-stick pan or wok. Cook on medium heat for 30 seconds then add garlic and fermented black beans. Cook for a further minute, stirring continuously. (note 3)
Add marinated beef strips into the pan, spreading beef out to a single layer. Turn the heat up to high, cook undisturbed, turning once. (note 4) Remove beef from the pan into a bowl and set aside.
Add remaining 1 tablespoon of oil, white parts of green onion, capsicum (bell peppers), onions and chilli (if using). Stir fry on high heat for 2 minutes.
Add beef back into the pan, along with all the juices. Add green parts of green onion, green parts of green onion and ~¼ cup of water. Stir fry for 30 seconds on high heat.
Taste, adjust for salt and pepper to taste (if required).
Serve immediately with some freshly cooked rice!