Stir the yogurt with 1 tablespoon ranch seasoning, reserve 1/4 cup of the clean mixture, coat the chicken with the remaining yogurt and refrigerate for 1 to 4 hours.
Combine the crushed chips with the remaining ranch seasoning in a shallow bowl and place the flour in another.
Lift each cutlet from the marinade, coat it lightly with flour, brush it with the reserved clean yogurt and press it hard into the chip crumbs, then chill the breaded pieces for 10 minutes.
Heat the canola oil in a wide heavy skillet to 335°F and fry 2 cutlets at a time for 4 to 5 minutes per side, adjusting the burner to hold 320°F to 335°F, until the coating is browned and the chicken reaches 165°F.
Drain the cutlets on a wire rack and let them stand for 5 minutes.
Toast the kaiser rolls, spread each with mayonnaise and stack with lettuce, 1 chicken cutlet and 1 tomato slice.