Fried Fish Sandwich with Tartar Sauce

1. In a small bowl mix together the cornmeal, flour, dry mustard and salt to make the fried fish coating and set aside.
2. Heat the oil in a heavy, deep, nonreactive pan (or a deep-fat fryer) until it reaches 365°F.
3. Meanwhile, submerge the fish into the buttermilk.  Remove and dip into the coating mixture, covering all areas of the fish.  Gently shake the pieces to remove any excess coating and place on a dish next to your frying area.
4. Test the oil using a deep fat thermometer to make sure it is at 365°F. Gently lower the fish pieces into the oil a few at a time, being sure not to overcrowd the oil as that will make the temperature drop.  When the fish begins to brown, flip them over and continue to fry until golden brown.
5. Remove the fish from the oil, sprinkle with salt if desired.  Continue to fry the rest of the fish, checking the oil temperature before adding each batch of fish.
6. Split the buns in half and spread the bottom half with tartar sauce.  Top with a piece of fried fish, lettuce, tomato and the top of the bun.  Serve immediately with additional tartar sauce if desired.

Adapted from the Legal Sea Foods Cookbook