Make mala seasoning mix. Combine gochugaru, Sichuan peppercorns, cumin, fennel, coriander seeds, and salt in a spice grinder. Pulse until finely ground. Set aside.

Heat oil in a large wok or saute pan over medium-high heat. Add pork and saute until browned and no longer pink. Add vegetables including onion, carrot, zucchini, napa cabbage, and scallions and saute until vegetables begin to soften, about 5 minutes.

Add garlic and ginger and saute for 1 more minute. Add mala seasoning mix and sesame oil, stirring to combine.

Pour dashi broth and add clams, shrimp, and mussels to the pot. Cover the pot and bring to a simmer. Continue to cook until the clams and mussel shells begin to open and the shrimp is cooked, about 7-8 minutes.

Meanwhile, cook noodles according to directions on package.

Remove lid and add heavy cream, fish sauce, and soy sauce, stirring to combine. Simmer for 1 more minute and adjust seasoning with salt and pepper.

Portion noodles into bowls and top with a generous amount of seafood and broth. Garnish with chopped scallions and serve immediately.