3.

When spaghetti is done, transfer to bowl with butter sauce using tongs. Add 1/4 cup (60ml) pasta-cooking water, then stir and toss pasta until it is evenly coated in sauce, any excess liquid has been absorbed, and a smooth, creamy sauce has formed. Transfer to serving bowls, top each bowl with reserved roe, and garnish with nori strips. Serve right away, mixing nori and roe garnish in with chopsticks before eating.