How to Make It
In a medium enameled cast-iron casserole, heat 3 inches of canola oil to 375°. Set a rack over a baking sheet.
In a large bowl, whisk the flour with the mustard powder, garlic, paprika and sparkling water.
Season the chicken with salt and pepper. Dip the chicken in the batter and let the excess drip off. Fry, turning, until golden and cooked through, 4 to 5 minutes. Transfer the chicken to the prepared rack to drain briefly.
Arrange eight of the waffles on a plate. Spread some mayo on the waffles and layer the lettuce, tomato, onion, pickles and fried chicken on top. Close the sandwiches and serve.