Cook the pasta: Bring a pot of salted water to a boil and cook your pasta until al dente. Reserve a bit of pasta water before draining, then set the pasta aside.
Marinate and sear the pork belly: Season the pork belly with soy sauce and white pepper. Heat a skillet over medium heat and sear the slices until golden brown and slightly crispy, about 2 minutes per side. Remove and set aside.
Sauté aromatics: In the same skillet, add chopped garlic and green onion. Sauté for about 1 minute until fragrant and lightly golden.
Make the sauce: Whisk together sugar, miso paste, soy sauce, and soy milk. Pour the mixture into the skillet and stir until the sauce is smooth and slightly thickened. Add a splash of pasta water if needed to loosen it up.
Toss with pasta: Add the cooked pasta back into the skillet and toss until every strand is coated in the creamy miso sauce.
Serve and garnish: Plate the pasta, top with the crispy pork belly, and garnish with fresh green onions. For extra richness, finish with a soft-boiled egg on top. Optional: serve with a soft-boiled egg!