I'm using striped bass, tilapia works great too.
Scale, gut, and clean the fish (the unpleasant part). I also like trimming off the fins. Score the skin of the fish a couple times diagonally for even cooking. Season both sides with salt, stuff the belly with onion slices and steam on a shallow heat-safe plate.
While the fish is steaming, prepare the vegetables. You'll need minced garlic, match-stick ginger, cilantro, and scallions cut into 1.5 in.
When the fish is cooked, take it out of the steamer, pour out the liquid, and discard the onion from the belly.
I transfered one of the fish to a separate plate (make sure it's shallow enough to hold the sauce) and added half of the scallions greens (saving the other half for the other fish).
Making the sauce for ONE fish - *on med-lo heat the entire time:
In a small pan, heat up some oil. Fry the scallion whites. After the scallions brown, add the garlic.
Let the garlic lightly brown, add the ginger. Add hot chili flake and about a tablespoon of sambal chili paste.
Deglaze with 1/4 cup soy sauce and a tablespoon fish sauce,. Let the sauce reduce for 30 seconds or so. Add3 tablespoons water and simmer for another 30 seconds (adjust to taste). Turn off heat and add the greens of the scallions.
Pour the sauce over the fish. Scoring the fish prior to cooking also helps the fish absorb the sauce. Garnish with cilantro and fried onions. Serve with rice.