Step 1Combine salt and pepper with oil in small bowl.
Step 2Gently rinse trout with cold water and pat dry. Rub fish inside and out with oil mixture.
Step 3Place 2 inches water in 14-inch skillet and add green onion halves, ginger, thin soy sauce and sweet soy sauce. Bring to boil, then reduce to simmer. Add trout, cover and cook until flesh begins to flake off bone, about 10 minutes. Gently lift fish onto plate, keeping fish intact.
Step 4Spoon small amount of cooking liquid onto fish, then top with thinly sliced green onions.