In a bowl, combine the thinly sliced pork with the onion, ginger, garlic, 1 tablespoon gochujang, 1 teaspoon soy sauce, 1 teaspoon sesame oil, and sugar. Mix well to coat. Let it marinate in the fridge for at least 4 hours, or overnight for the best flavor.
To cook the pork you have two options. You can stir-fry the pork in a hot wok with a little oil until cooked through and slightly caramelized. Alternatively, for an easier (and Marilla-approved) method, spread the pork in a single layer on a sheet pan. Broil on high or use your oven's air-fry setting at 400°F (200°C) for about 8-10 minutes. Keep an eye on it so it doesn't overcook or dry out!
While the pork is cooking, grab a very large mixing bowl. Combine the remaining 2 tablespoons of gochujang, gochugaru, 1 teaspoon soy sauce, and 1 teaspoon sesame oil. Whisk them together until you have a thick, spicy paste.
Boil your noodles according to the package instructions. Drain them well.
While the noodles are still hot, add them directly into the large bowl with the sauce base. Add the cooked pork, sliced tofu puffs, chopped kimchi, and julienned cucumber. Toss everything together vigorously until the noodles are evenly coated in the sauce and the ingredients are well distributed.
Garnish with green onions and toasted sesame seeds.