Preheat oven to 400F/204C.
MAKE SAUCE/GLAZE: Whisk together all ingredients in a small glass measuring cup or bowl. If you want a slightly thicker glaze, whisk in the cornstarch and microwave sauce for 45-60 seconds. I do this. If you prefer a thin glaze, don't use the cornstarch.
PREPARE TROUT FILLETS: Line a pan, large enough to fit the trout, with parchment or tin foil sprayed with oil. Generously sprinkle trout with salt and pepper. Sprinkle chopped green onions over fish. Drizzle on half the sauce/glaze, reserving the rest for serving.
ROAST/BAKE TROUT: for 8-11 minutes depending on the thickness of the fish. Note 1. Remove from oven and cut into portions. If you want to remove skin, slip a spatula between the bottom of the flesh and skin, then lift trout off. Drizzle on the remaining sauce and garnish with chopped parsley, green onions or other fresh herbs if desired.