Brine: Combine 480 ml (2 cups) water with 30 g (2 tbsp) salt and 30 g (2 tbsp) sugar, submerge chicken for 20 minutes - results in juicier meat via osmosis.
Prep fries: Cut potatoes into 10 mm (3/8 inch) sticks, rinse, then soak in ice water 30 minutes to remove surface starch for crisper fries.
Coating mix: Whisk flour, cornstarch, 10 g (2 tsp) smoked paprika, 5 g (1 tsp) garlic powder, salt and pepper. Beat eggs with 120 ml (1/2 cup) milk or buttermilk.
Dry and coat chicken: Pat chicken dry, dredge in flour mix, dip in egg, then back in flour. Press firmly to form an even crust, essential for even browning.
Fry fries first: Heat oil to 160 C (320 F). Fry potatoes 4-5 minutes until softened but not brown. Drain and cool on a rack.
Fry chicken: Increase oil to 175 C (350 F). Fry chicken 5-7 minutes until golden and internal temp 74 C (165 F). Rest on a rack 5 minutes to set crust and redistribute juices.
Finish fries: Return fries to 190 C (375 F) and fry 2-3 minutes to color and crisp. Salt immediately after removing from oil.
Assemble: Toast buns, spread sauce, place chicken, add pickles and lettuce. Serve fries hot with dipping sauce. Notice the contrast between the peppery, crunchy crust and the tender internal texture.