Sift the self-rising flour, cornstarch, salt, and sugar into a large bowl, then whisk until the dry mixture looks evenly blended. Sifting breaks up clumps so the finished batter fries into a smoother, lighter shell.

Pour in the Seltzer water gradually while whisking until the batter is slightly thicker than pancake batter. It should slowly coat a spoon; stir in a little more seltzer if it feels too stiff or flour if it runs off too quickly.

Cut the chicken breasts into even strips, about 1/2 inch thick, and season the pieces with salt. Uniform strips cook at a similar pace and help prevent the outside from darkening before the centers are done.

Coat each chicken strip completely in batter just before frying. The chicken should disappear under the batter with no dry patches showing through.

Lower the coated strips carefully into preheated oil and fry for about 10 minutes until rich golden brown. The batter may remain pale and white-looking during the early minutes, then deepen in color as the sizzling softens slightly near the end.