Thaw fish, if frozen.
Cut into serving-size pieces.
Cut potatoes in uniform strips, slightly larger than for French fries.
To make chips: Deep fry potato strips until golden brown in Crisco heated to 375°F. (about 7-8 minutes).
Remove, drain on paper towels, and keep warm.
In medium bowl, combine first 1/4 cup flour and salt.
Make well in center; add egg yolk, water, and melted Crisco.
Stir until batter is smooth.
Fold in egg white.
Dip fish in the remaining 1/4 cup flour, then into batter.
Deep fry fish until golden brown in Crisco heated to 375° (about 1 1/2 minutes on each side.) Sprinkle fish with vinegar, if desired.
Sprinkle fish and chips with salt.