Bring large pot of lightly salted water to a boil. Cook pasta according to package directions. Add peas, bell pepper, and green onion to pasta water 5 minutes before estimated cooking time is up.
Meanwhile, place salmon in a microwave-safe dish, flesh-side-down; cover with plastic wrap. Microwave on 50 percent power about 5 minutes, or until fishis cooked through. When it's cool enough to handle, remove skin and any bones and divide into about 1 inch pieces.
Drain pasta and vegetables, reserving 1/3 cup cooking water; transfer to large bowl. Toss pasta with sour cream, dill, salt, pepper, and reserved pasta water. Gently fold in salmon. Divide among 4 serving plates and garnish with dill.