Arrange filets on one cake rack (skin side down); sprinkle with salt, pepper and lime juice. Line cast iron pan with foil, letting it overhang by 12" all around. Spread wood chips in pan and top with empty rack. Place rack with herring on top. Draw up the foil to cover all and seal the joins to make a smoking chamber. Poke a small hole at the top to let some smoke escape. Place pan over high heat until you start to see smoke. Reduce heat to med. and let the smoke flavour and cook the fish for 20-30 min. Remove from heat and tear small hole in the foil to let smoke out. Let fish sit for 10 min. until smoke dissipates. Serves 2.