Mix the burger mixture all together in a bowl and form into patties. Cover and place in the fridge for 30-40mins until firm.
Once firm now you can coat them. Dip into the flour, then into the beaten egg mixture and then into the breadcrumbs mixed with the Cajun spice.
Fry in very hot oil for 1-2 minutes a side until the breadcrumbs are crisp and golden. Place in a roasting tray and place in a 180°c oven for 10-15 minutes until the burgers are cooked all the way through.
Now build them up. Mix the lemon mayo by zesting the lemon into the mayonnaise and squeezing a small bit of juice in.
Spoon on the mayo onto toasted brioche buns, lay on the lettuce and then the crispy burger on top. Enjoy.