Place KEEN’S Mustard Powder and flour into a freezer bag. In a medium bowl whisk together the egg and milk. Place the breadcrumbs into another freezer bag.
Toss tenderloins in the flour mix and remove, shaking off excess flour. Dip the floured tenderloins into the egg wash and then toss into breadcrumbs, pressing crumbs onto chicken. Repeat process with the remaining chicken, flour, egg wash and crumbs until all chicken is coated.
Heat oil in a large frying pan over medium heat and pan-fry chicken for 3 minutes on each side until golden brown and cooked.
Spread each dinner roll with mayonnaise and fill with schnitzels, ham, cheese and lettuce.
Once chicken tenderloins are crumbed refrigerate for 30 minutes, this helps the crumbs to stick better.