If using dried rice noodles, soak in water for at least 2 hours. If you are using fresh sheets of rice noodles, they come in one large sheet or pre-cut. If you are using one large sheet like me, cut into 1-2 inch wide (I like it 2-inch wide, but it's up to you)
Put the sirloin in the freezer for 15 minutes before cutting. This helps me to cut it thinner. Make sure you cut the meat across the grain so you get tender meat
Put all ingredients for marinating the beef and let it marinate for 30 minutes while you are preparing other things
Toss the noodles in dark soy sauce and set aside
Cooking:
Preheat the skillet/wok over high heat until really hot. You can start seeing smoke rising from the wok. Add 2 Tbsp of oil. Add the rice noodles, spreading it across the skillet/work in one layer and let it fry for about 1 minute on one side , it might be longer for dried noodles and then flip over and cook another 1 minute. The noodles will continue to get soften. Don't overstir the noodles or they will break apart and turn choppy. We just want to give the noodles a bit of that "charred" aroma
Place the noodles spread out on a large serving platter for everyone to share or into an individual platter
Scrap any crust off the skillet/wok, if any. Add in about 1 Tbsp of oil, swirl it quickly to cover the base and add the beef slices. Don't stir and let them cook for about 1 minute and then a quick stir to separate them and dish out and pile on top of the hor fun
Prepare the gravy:
Bring the wok back to hot again. Lower the heat to medium. Add 2 Tbsp of oil. Add garlic and stir fry for about 30 seconds. Then add the black bean paste and stir fry for another 30 seconds. Add the beef broth followed by the seasonings. Bring it to simmer
Add the greens to the gravy and cook for about 1 minute. Have a taste and adjust seasonings to your preference. Combine the cornstarch and water. Add into the gravy and stir until gravy thickens. Beat one egg with a fork to loosen. Drizzle into the gravy while one hand is stirring. Turn off the heat. You don't want to overcook the egg
Put everything together:
Pour the gravy along with the greens on top of the hor fun and beef. Serve immediately