Mix the beef with vinegar, black pepper, 1/2 tsp salt, oyster sauce. Marinate in the fridge for about an hour.
Place a medium-sized pan in medium heat.
Pour the olive oil and heat it up.
Lower the heat. Add the beef and fry until its reddishness fades.
Add Yardlong bean and carrots and stir.
Add the egg and stir vigorously. The egg should congeal into small pieces. Cut up the bigger pieces with the spatula.
Pour mustard oil, then add cauliflower and stir.
Add chili powder, biryani masala, green chilies, and salt to taste. Stir for 2-3 minutes.
Add 1 tbsp water, mix, cover the pan and wait 3-4 minutes.
Uncover the pan, stir on medium-high flame for a minute, or until the water evaporates.
Serve hot with cucumber and/or tomato slices.
