Source: http://meal5.com/simple-healthy-recipes/how-to-make-a-whitefish-sandwich

Can’t go wrong here with this lightly pan-fried fish sandwich. Walleye and tilapia are great choices, and buying it as fresh as possible will make it even better. A simple egg wash helps the flour stick nicely to the fish and will give it the right amount of crispiness while keeping it out of greasy territory. You’ll know it’s done when it turns golden on the outside, and white and flaky on the inside. Serve in a hoagie bun with Tangy Tartar Sauce. It's easy to make and oh so good!

Ingredients1¼ lb. fresh walleye or tilapia½ cup flour1 egg4 hamburger or hoagie buns Salt and pepper Tangy Tartar Sauce Ingredients1 Tbsp. light mayonnaise1 Tbsp. non-fat plain Greek yogurt 1 Tbsp. sweet pickle relish1 tsp. balsamic vinegar

Step 1:

Part 1: Prepare fish

Rinse fresh fish and pat dry with paper towel.In a small bowl, whisk 1 egg, plus 1 teaspoon water together until frothy.

Step 2:

Part 2: Prepare coating

Pour egg wash into a flat dish.Put flour into a flat dish.

Step 3:

Part 3: Coat fish

Dip fresh fish into egg wash covering completely, then dredge through flour to coat lightly.Season with salt and pepper.

Step 4: Cook Fish

Over medium heat place fish in skillet or griddle.Cook until golden brown (3-4 minutes)Turn fish over, allowing second side to cook until fish is done(2-3 minutes or when fish turns white and flakes apart easily). It doesn't take long so keep an eye on it :)Butter both sides of bun and toast until golden brown. Remove and set aside.