Optional for serving: Lime wedges; sliced chiles; Nuoc Cham dipping sauce*, cooked; room-temperature rice vermicelli; roasted peanuts; rice crackers (banh da); curly-leaf lettuce; fresh mint
Prepare marinade: In glass or ceramic shallow dish place salt, sugar, dried dill, turmeric, galangal and white pepper; stir to combine. Add 3 tablespoons oil; stir to combine. Place fish in dish; gently swirl it to coat with marinade; turn and gently swirl to coat. Cover with plastic wrap and place in refrigerator for 1 hour.
Heat about 2 tablespoons corn oil on medium-high heat in nonstick skillet large enough to hold fish. On a separate burner on medium-high, heat "fajita-style" grill pan (cast iron griddle that has a heat-proof trivet, often made of wood, that sits so it can be carried sizzling to the table). Cook catfish in nonstick skillet until brown and crispy and cooked through, about 3 to 5 minutes each side.
Place heated grill pan on trivet. Place two large leafs of curly-leaf lettuce on "fajita" pan and top with fish. Scatter onion and dill over fish and next to fish. Add green onions to pan used to cook fish; cook 1 or 2 minutes on medium-high heat. Place next to fish. Carry sizzling fish to table.
Serving: Provide each guest with a bowl. In center of table place a bowl of lime wedges, sliced chilies, nuoc cham dipping sauce, roasted peanuts and cooked rice vermicelli. Also provide a platter of lettuce and sprigs of fresh mint. Guests place some noodles in bottom of their bowls. They can assemble their serving to suit their taste. Generally noodles go it first, then a small serving of catfish topped with lettuce and mint, then a good spoonful of nuoc cham. Next add some peanuts and, if you like, a sliver of chili and a squeeze of lime juice.
*COOK'S NOTES: Galingal is a knobby rhizome with a ginger-peppery flavor. It's available fresh and dried (confectioners') in Asian markets. Some supermarkets with large Asian specialty section carry it dried. The dried, confectioners' version is sometimes labeled Laos powder or Laos ginger.
Nuoc Cham dipping sauce is made by combining 1/3 cup fish sauce, 3 tablespoons water, 5 tablespoons sugar, 1/2 cup fresh lime juice; stir until sugar dissolves. Add 1 tablespoon shredded carrot.
To cook small dried rice vermicelli, boil for about 4 minutes, drain, then refresh with cold water; drain.Makes 4 to 6 Source: