In a cold nonstick pan (or wok), add the oil and black bean paste. Place it over medium heat and fry for about 2 minutes. Make sure to keep stirring it.
Once you see the bubbles in the middle, give it about 30 seconds to 1 minute. Turn the heat off. Set aside.
Finely mince the ginger. Roughly chop the onion. Thinly slice the green onions. Cut the garlic chives into long strips. Cut the button mushrooms into quarters. Thinly slice the cucumber for garnish.
Cut the pork belly into nice, bite-sized pieces.
Blanch the seafood and drain.
Add the cooking oil (2 tbsp) to a wok. (You can reuse the one that you fried black bean paste with.)
Add the lard (if using) and heat it over medium heat. Once it's nice and hot, add the pork and render out the fat for 2 to 3 minutes.
When the pork is nicely browned, add the ginger and stir-fry for 30 seconds. Add the soy sauce and give it a good stir for another 1 minute. Be careful! The oil might splatter.
Increase the heat to high. Add the onion and green onions. Stir-fry it for about 2 minutes or until they're slightly softened.
Add the blanched seafood, mushrooms, sugar, oyster sauce, chicken bouillon powder, and MSG (if using). Stir-fry it for another 2 minutes.
Add the fried black bean paste and stir it all together for about 2 minutes.
Once everything is well coated, reduce the heat to medium, add the water and bring it to a boil. Once it comes to a boil, carefully add the cornstarch slurry (1 tsp cornstarch + 1 tbsp water) and stir. Cover and keep it warm until the noodles are ready.
Cook the noodles according to the package instructions.
Bring the sauce to a boil over high heat and add the drained noodles. Quickly toss it around for about 1 to 2 minutes and turn the heat off. Add the garlic chives and drizzle with the sesame oil. Give it a final mix.
Transfer to a large platter. Garnish with the cucumber.