Divide the mince into 4 equal portions and shape them into patties sized to fit the burger buns. Season with salt and freshly ground pepper.
Mix the plain flour with the spices, season with salt and freshly ground pepper and tip it onto a deep plate.Tip the blitzed cornflakes onto another plate, and the beaten egg onto a third.
Turn the chicken patties in the seasoned flour, then thoroughly in the beaten egg and finally in the cornflakes.
Heat a generous glug of neutral oil in a frying pan and fry the chicken patties until golden and crisp on both sides and cooked through.You can also cook them in an air fryer at 190°C for about 18 minutes, or in a fan oven at 200°C for 18-22 minutes - depending on the thickness of the patties. Spray them lightly with cooking spray before they go into the air fryer or oven.
Meanwhile, stir the mayonnaise together with the Dijon mustard, and warm the burger buns in a frying pan, in the oven, in a toaster or in the air fryer.
Spread the top and bottom halves of the buns with the mayonnaise, place a chicken patty on each base, top with lettuce and finish with the top half of the bun. Serve immediately.