The quality and freshness of the fish is crucial for the success of the dish. Purchase the fish from a Japanese fish shop that specializes in sashimi, or a reliable fishmonger. To facilitate the very fine shredding of the radish and carrot, use a mandolin or the fine shredding disc of a food processor.
Chill fish until firm. Cut into paper-thin, 2-inch-long slices against the grain; set aside.
In separate bowls, cover radishes and carrots with cold water; set aside until ready to assemble salad. Then rinse and squeeze out excess water.
To assemble: Toss fish slices with marinade ingredients. Place fish in center of a platter. Arrange daikon and carrot shreds around fish. Scatter fresh and pickled ginger, the pickled scallions, lime leaves, chiles, green onions and cilantro over fish. Sprinkle with peanuts and sesame seeds.
Just before serving, squeeze the lime or lemon juice over all. It is customary for everyone to join in and toss the salad. Using chopsticks, each diner digs from the bottom of the salad and lifts the ingredients to mix together.
When the salad is fully tossed, taste for seasoning. Adjust with more sesame oil, lime juice, salt and/or some of the juices from the pickled vegetables.
Garnish with shrimp chips or fried rice stick noodles.
Serves 4 to 6.
NOTE: Bottled pickled ginger and pickled scallions may be found in Chinese markets. Kaffir lime leaves may be found in Thai grocery stores. If kaffir leaves are not available, omit or substitute domestic lime leaves.