Make sure you get a fresh cut of trout. If the trout doesn't appear shiny, and a rich, deep reddish-pink, hold off until the fresh stuff comes to your fishmonger. Buy 1 pound filet. Unwrap, and salt and pepper both sides, being especially generous on the skin side (especially if you love eating crispy skin, like I do).
Turn on over broiler. Place oven rack in the middle, higher (closer to the flame) if you like more crisp on top, less done in the middle.
Drizzle a bit of olive oil in a baking dish, spread it around, and place fish on top, skin side down. Then generously spread the hoisin sauce on top of the fish's flesh. Crush a bit more salt on top, and put her in the oven.
Cook 8 - 10 minutes, or until ready to your liking. I wait until the bottom (skin side) is really bubbling, so the skin gets caramelized and crispy.
Serve immediately, with some chopped cilantro and/or a squeeze of lime if desired.