Mix the vinegar, Worcestershire, salt, pepper and liquid smoke, if using, in a small dish until the salt dissolves. Pour over the fish; close the bag and turn it to evenly distribute the marinade over all the surfaces of the fish. Refrigerate for 30 minutes.
Meanwhile, heat a gas grill to high or prepare a charcoal grill and let burn until coals are covered with gray ash. Move the coals to one side of the grill or turn off some of the burners on the gas grill.
Drain the wood chips and place them on the hot coals. (Or, place on a double thickness of foil and place the packet over the heat source on the gas grill.) Put the grill grate in place and cover the grill to let the smoke develop and the grill grate heat up.
Remove the fish from the marinade and pat dry. If using bacon drippings, brush the fish with that. Place the fish on the grill away from the heat source. Cook, without turning, until the fish almost flakes easily with a fork, 13 to 15 minutes. (For thin fillets, cook 8 to 10 minutes.)
Brush with more bacon fat if desired, then remove fish with a thin metal spatula. Serve warm topped with tomatoes and chives. Or, refrigerate up to 3 days and serve cold or at room temperature.
Nutrition information per serving (with bacon drippings used):