In roasting pan combine black pepper, san bai su, lemon juice, sesame oil and tahini. Whisk to combine. Using a sharp knife, score several diagonal lines along the length of fish, down to spine, on either side. Place fish in pan and marinate 2 - 4 hours at room temperature. After marination, preheat grill or broiler.
Blanch greens in a large pot of boiling, salted water, just until the water returns to a boil. Refresh in ice water and drain. On a large baking sheet, arrange greens, overlapping, to form a rectangle as long as the fish and twice as wide as the fish. Place fish in middle and wrap the greens over so only the head and tail are exposed. Seal with a piece of butchers string or dental floss. Place fish on grill. Cook 7 - 12 minutes per side, until greens, head and tail blacken. It will take 2 spatulas, one at the head and one at the tail, to turn fish, don't be concerned about greens sticking. To test for doneness, try pulling out a dorsal fin from the top of the fish. If it slides out easily, it's done.
To serve, place the whole fish on a serving platter. Using a dull knife and soup spoon, scrape of any remaining skin and remove fins. Spoon half reserved marinade over top. Cut along spine first and serve the top fillet. Lift tail, insert knife between bones and flesh, and run it along the length. All, or most, of the bones should easily lift out. Spoon on remaining marinade and serve second fillet.
* San bai su: A Japanese season made from equal parts mirin, soy sauce and brown rice vinegar.
c.1997, M.S. Milliken & S. Feniger, all rights reserved